Calculus Examples

$x^{\frac{4}{5}} {(x - 6)}^{2}$

Step 1

Write $x^{\frac{4}{5}} {(x - 6)}^{2}$ as a function.

$f (x) = x^{\frac{4}{5}} {(x - 6)}^{2}$

Step 2

Find the first derivative of the function.

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Step 2.1

Rewrite ${(x - 6)}^{2}$ as $(x - 6) (x - 6)$ .

$\frac{d}{d x} [x^{\frac{4}{5}} ((x - 6) (x - 6))]$

Step 2.2

Expand $(x - 6) (x - 6)$ using the FOIL Method.

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Step 2.2.1

Apply the distributive property.

$\frac{d}{d x} [x^{\frac{4}{5}} (x (x - 6) - 6 (x - 6))]$

Step 2.2.2

Apply the distributive property.

$\frac{d}{d x} [x^{\frac{4}{5}} (x \cdot x + x \cdot - 6 - 6 (x - 6))]$

Step 2.2.3

Apply the distributive property.

$\frac{d}{d x} [x^{\frac{4}{5}} (x \cdot x + x \cdot - 6 - 6 x - 6 \cdot - 6)]$

Step 2.3

Simplify and combine like terms.

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Step 2.3.1

Simplify each term.

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Step 2.3.1.1

Multiply $x$ by $x$ .

$\frac{d}{d x} [x^{\frac{4}{5}} (x^{2} + x \cdot - 6 - 6 x - 6 \cdot - 6)]$

Step 2.3.1.2

Move $- 6$ to the left of $x$ .

$\frac{d}{d x} [x^{\frac{4}{5}} (x^{2} - 6 \cdot x - 6 x - 6 \cdot - 6)]$

Step 2.3.1.3

Multiply $- 6$ by $- 6$ .

$\frac{d}{d x} [x^{\frac{4}{5}} (x^{2} - 6 x - 6 x + 36)]$

Step 2.3.2

Subtract $6 x$ from $- 6 x$ .

$\frac{d}{d x} [x^{\frac{4}{5}} (x^{2} - 12 x + 36)]$

Step 2.4

Differentiate using the Product Rule which states that $\frac{d}{d x} [f (x) g (x)]$ is $f (x) \frac{d}{d x} [g (x)] + g (x) \frac{d}{d x} [f (x)]$ where $f (x) = x^{\frac{4}{5}}$ and $g (x) = x^{2} - 12 x + 36$ .

$x^{\frac{4}{5}} \frac{d}{d x} [x^{2} - 12 x + 36] + (x^{2} - 12 x + 36) \frac{d}{d x} [x^{\frac{4}{5}}]$

Step 2.5

Differentiate.

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Step 2.5.1

By the Sum Rule, the derivative of $x^{2} - 12 x + 36$ with respect to $x$ is $\frac{d}{d x} [x^{2}] + \frac{d}{d x} [- 12 x] + \frac{d}{d x} [36]$ .

$x^{\frac{4}{5}} (\frac{d}{d x} [x^{2}] + \frac{d}{d x} [- 12 x] + \frac{d}{d x} [36]) + (x^{2} - 12 x + 36) \frac{d}{d x} [x^{\frac{4}{5}}]$

Step 2.5.2

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$x^{\frac{4}{5}} (2 x + \frac{d}{d x} [- 12 x] + \frac{d}{d x} [36]) + (x^{2} - 12 x + 36) \frac{d}{d x} [x^{\frac{4}{5}}]$

Step 2.5.3

Since $- 12$ is constant with respect to $x$ , the derivative of $- 12 x$ with respect to $x$ is $- 12 \frac{d}{d x} [x]$ .

$x^{\frac{4}{5}} (2 x - 12 \frac{d}{d x} [x] + \frac{d}{d x} [36]) + (x^{2} - 12 x + 36) \frac{d}{d x} [x^{\frac{4}{5}}]$

Step 2.5.4

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 1$ .

$x^{\frac{4}{5}} (2 x - 12 \cdot 1 + \frac{d}{d x} [36]) + (x^{2} - 12 x + 36) \frac{d}{d x} [x^{\frac{4}{5}}]$

Step 2.5.5

Multiply $- 12$ by $1$ .

$x^{\frac{4}{5}} (2 x - 12 + \frac{d}{d x} [36]) + (x^{2} - 12 x + 36) \frac{d}{d x} [x^{\frac{4}{5}}]$

Step 2.5.6

Since $36$ is constant with respect to $x$ , the derivative of $36$ with respect to $x$ is $0$ .

$x^{\frac{4}{5}} (2 x - 12 + 0) + (x^{2} - 12 x + 36) \frac{d}{d x} [x^{\frac{4}{5}}]$

Step 2.5.7

Add $2 x - 12$ and $0$ .

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) \frac{d}{d x} [x^{\frac{4}{5}}]$

Step 2.5.8

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = \frac{4}{5}$ .

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) (\frac{4}{5} x^{\frac{4}{5} - 1})$

Step 2.6

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) (\frac{4}{5} x^{\frac{4}{5} - 1 \cdot \frac{5}{5}})$

Step 2.7

Combine $- 1$ and $\frac{5}{5}$ .

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) (\frac{4}{5} x^{\frac{4}{5} + \frac{- 1 \cdot 5}{5}})$

Step 2.8

Combine the numerators over the common denominator.

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) (\frac{4}{5} x^{\frac{4 - 1 \cdot 5}{5}})$

Step 2.9

Simplify the numerator.

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Step 2.9.1

Multiply $- 1$ by $5$ .

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) (\frac{4}{5} x^{\frac{4 - 5}{5}})$

Step 2.9.2

Subtract $5$ from $4$ .

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) (\frac{4}{5} x^{\frac{- 1}{5}})$

Step 2.10

Move the negative in front of the fraction.

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) (\frac{4}{5} x^{- \frac{1}{5}})$

Step 2.11

Combine $\frac{4}{5}$ and $x^{- \frac{1}{5}}$ .

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) \frac{4 x^{- \frac{1}{5}}}{5}$

Step 2.12

Move $x^{- \frac{1}{5}}$ to the denominator using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13

Simplify.

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Step 2.13.1

Apply the distributive property.

$x^{\frac{4}{5}} (2 x) + x^{\frac{4}{5}} \cdot - 12 + (x^{2} - 12 x + 36) \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.2

Apply the distributive property.

$x^{\frac{4}{5}} (2 x) + x^{\frac{4}{5}} \cdot - 12 + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3

Combine terms.

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Step 2.13.3.1

Multiply $x^{\frac{4}{5}}$ by $x$ by adding the exponents.

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Step 2.13.3.1.1

Move $x$ .

$x \cdot x^{\frac{4}{5}} \cdot 2 + x^{\frac{4}{5}} \cdot - 12 + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.1.2

Multiply $x$ by $x^{\frac{4}{5}}$ .

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Step 2.13.3.1.2.1

Raise $x$ to the power of $1$ .

$x^{1} x^{\frac{4}{5}} \cdot 2 + x^{\frac{4}{5}} \cdot - 12 + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.1.2.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$x^{1 + \frac{4}{5}} \cdot 2 + x^{\frac{4}{5}} \cdot - 12 + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.1.3

Write $1$ as a fraction with a common denominator.

$x^{\frac{5}{5} + \frac{4}{5}} \cdot 2 + x^{\frac{4}{5}} \cdot - 12 + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.1.4

Combine the numerators over the common denominator.

$x^{\frac{5 + 4}{5}} \cdot 2 + x^{\frac{4}{5}} \cdot - 12 + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.1.5

Add $5$ and $4$ .

$x^{\frac{9}{5}} \cdot 2 + x^{\frac{4}{5}} \cdot - 12 + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.2

Move $2$ to the left of $x^{\frac{9}{5}}$ .

$2 \cdot x^{\frac{9}{5}} + x^{\frac{4}{5}} \cdot - 12 + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.3

Move $- 12$ to the left of $x^{\frac{4}{5}}$ .

$2 x^{\frac{9}{5}} - 12 \cdot x^{\frac{4}{5}} + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.4

Combine $x^{2}$ and $\frac{4}{5 x^{\frac{1}{5}}}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{x^{2} \cdot 4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.5

Move $4$ to the left of $x^{2}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 \cdot x^{2}}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.6

Move $x^{\frac{1}{5}}$ to the numerator using the negative exponent rule $\frac{1}{b^{n}} = b^{- n}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{2} x^{- \frac{1}{5}}}{5} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.7

Multiply $x^{2}$ by $x^{- \frac{1}{5}}$ by adding the exponents.

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Step 2.13.3.7.1

Move $x^{- \frac{1}{5}}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 (x^{- \frac{1}{5}} x^{2})}{5} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.7.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{- \frac{1}{5} + 2}}{5} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.7.3

To write $2$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{- \frac{1}{5} + 2 \cdot \frac{5}{5}}}{5} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.7.4

Combine $2$ and $\frac{5}{5}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{- \frac{1}{5} + \frac{2 \cdot 5}{5}}}{5} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.7.5

Combine the numerators over the common denominator.

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{- 1 + 2 \cdot 5}{5}}}{5} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.7.6

Simplify the numerator.

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Step 2.13.3.7.6.1

Multiply $2$ by $5$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{- 1 + 10}{5}}}{5} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.7.6.2

Add $- 1$ and $10$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.8

Combine $- 12$ and $\frac{4}{5 x^{\frac{1}{5}}}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + x \frac{- 12 \cdot 4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.9

Multiply $- 12$ by $4$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + x \frac{- 48}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.10

Combine $x$ and $\frac{- 48}{5 x^{\frac{1}{5}}}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{x \cdot - 48}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.11

Move $- 48$ to the left of $x$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{- 48 \cdot x}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.12

Move $x^{\frac{1}{5}}$ to the numerator using the negative exponent rule $\frac{1}{b^{n}} = b^{- n}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{- 48 x \cdot x^{- \frac{1}{5}}}{5} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.13

Multiply $x$ by $x^{- \frac{1}{5}}$ by adding the exponents.

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Step 2.13.3.13.1

Move $x^{- \frac{1}{5}}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{- 48 (x^{- \frac{1}{5}} x)}{5} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.13.2

Multiply $x^{- \frac{1}{5}}$ by $x$ .

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Step 2.13.3.13.2.1

Raise $x$ to the power of $1$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{- 48 (x^{- \frac{1}{5}} x^{1})}{5} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.13.2.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{- 48 x^{- \frac{1}{5} + 1}}{5} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.13.3

Write $1$ as a fraction with a common denominator.

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{- 48 x^{- \frac{1}{5} + \frac{5}{5}}}{5} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.13.4

Combine the numerators over the common denominator.

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{- 48 x^{\frac{- 1 + 5}{5}}}{5} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.13.5

Add $- 1$ and $5$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{- 48 x^{\frac{4}{5}}}{5} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.14

Move the negative in front of the fraction.

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} - \frac{48 x^{\frac{4}{5}}}{5} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.15

Combine $36$ and $\frac{4}{5 x^{\frac{1}{5}}}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{36 \cdot 4}{5 x^{\frac{1}{5}}}$

Step 2.13.3.16

Multiply $36$ by $4$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 2.13.3.17

To write $2 x^{\frac{9}{5}}$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$- 12 x^{\frac{4}{5}} + 2 x^{\frac{9}{5}} \cdot \frac{5}{5} + \frac{4 x^{\frac{9}{5}}}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 2.13.3.18

Combine $2 x^{\frac{9}{5}}$ and $\frac{5}{5}$ .

$- 12 x^{\frac{4}{5}} + \frac{2 x^{\frac{9}{5}} \cdot 5}{5} + \frac{4 x^{\frac{9}{5}}}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 2.13.3.19

Combine the numerators over the common denominator.

$- 12 x^{\frac{4}{5}} + \frac{2 x^{\frac{9}{5}} \cdot 5 + 4 x^{\frac{9}{5}}}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 2.13.3.20

Multiply $5$ by $2$ .

$- 12 x^{\frac{4}{5}} + \frac{10 x^{\frac{9}{5}} + 4 x^{\frac{9}{5}}}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 2.13.3.21

Add $10 x^{\frac{9}{5}}$ and $4 x^{\frac{9}{5}}$ .

$- 12 x^{\frac{4}{5}} + \frac{14 x^{\frac{9}{5}}}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 2.13.3.22

To write $- 12 x^{\frac{4}{5}}$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$- 12 x^{\frac{4}{5}} \cdot \frac{5}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 2.13.3.23

Combine $- 12 x^{\frac{4}{5}}$ and $\frac{5}{5}$ .

$\frac{- 12 x^{\frac{4}{5}} \cdot 5}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 2.13.3.24

Combine the numerators over the common denominator.

$\frac{- 12 x^{\frac{4}{5}} \cdot 5 - 48 x^{\frac{4}{5}}}{5} + \frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 2.13.3.25

Multiply $5$ by $- 12$ .

$\frac{- 60 x^{\frac{4}{5}} - 48 x^{\frac{4}{5}}}{5} + \frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 2.13.3.26

Subtract $48 x^{\frac{4}{5}}$ from $- 60 x^{\frac{4}{5}}$ .

$\frac{- 108 x^{\frac{4}{5}}}{5} + \frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 2.13.3.27

Move the negative in front of the fraction.

$- \frac{108 x^{\frac{4}{5}}}{5} + \frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 2.13.4

Reorder terms.

$\frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}} - \frac{108 x^{\frac{4}{5}}}{5}$

Step 3

Find the second derivative of the function.

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Step 3.1

By the Sum Rule, the derivative of $\frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}} - \frac{108 x^{\frac{4}{5}}}{5}$ with respect to $x$ is $\frac{d}{d x} [\frac{14 x^{\frac{9}{5}}}{5}] + \frac{d}{d x} [\frac{144}{5 x^{\frac{1}{5}}}] + \frac{d}{d x} [- \frac{108 x^{\frac{4}{5}}}{5}]$ .

$f'' (x) = \frac{d}{d x} (\frac{14 x^{\frac{9}{5}}}{5}) + \frac{d}{d x} (\frac{144}{5 x^{\frac{1}{5}}}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.2

Evaluate $\frac{d}{d x} [\frac{14 x^{\frac{9}{5}}}{5}]$ .

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Step 3.2.1

Since $\frac{14}{5}$ is constant with respect to $x$ , the derivative of $\frac{14 x^{\frac{9}{5}}}{5}$ with respect to $x$ is $\frac{14}{5} \frac{d}{d x} [x^{\frac{9}{5}}]$ .

$f'' (x) = \frac{14}{5} \cdot \frac{d}{d x} (x^{\frac{9}{5}}) + \frac{d}{d x} (\frac{144}{5 x^{\frac{1}{5}}}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.2.2

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = \frac{9}{5}$ .

$f'' (x) = \frac{14}{5} \cdot (\frac{9}{5} x^{\frac{9}{5} - 1}) + \frac{d}{d x} (\frac{144}{5 x^{\frac{1}{5}}}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.2.3

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$f'' (x) = \frac{14}{5} \cdot (\frac{9}{5} x^{\frac{9}{5} - 1 \cdot \frac{5}{5}}) + \frac{d}{d x} (\frac{144}{5 x^{\frac{1}{5}}}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.2.4

Combine $- 1$ and $\frac{5}{5}$ .

$f'' (x) = \frac{14}{5} \cdot (\frac{9}{5} x^{\frac{9}{5} + \frac{- 1 \cdot 5}{5}}) + \frac{d}{d x} (\frac{144}{5 x^{\frac{1}{5}}}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.2.5

Combine the numerators over the common denominator.

$f'' (x) = \frac{14}{5} \cdot (\frac{9}{5} x^{\frac{9 - 1 \cdot 5}{5}}) + \frac{d}{d x} (\frac{144}{5 x^{\frac{1}{5}}}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.2.6

Simplify the numerator.

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Step 3.2.6.1

Multiply $- 1$ by $5$ .

$f'' (x) = \frac{14}{5} \cdot (\frac{9}{5} x^{\frac{9 - 5}{5}}) + \frac{d}{d x} (\frac{144}{5 x^{\frac{1}{5}}}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.2.6.2

Subtract $5$ from $9$ .

$f'' (x) = \frac{14}{5} \cdot (\frac{9}{5} x^{\frac{4}{5}}) + \frac{d}{d x} (\frac{144}{5 x^{\frac{1}{5}}}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.2.7

Combine $\frac{9}{5}$ and $x^{\frac{4}{5}}$ .

$f'' (x) = \frac{14}{5} \cdot \frac{9 x^{\frac{4}{5}}}{5} + \frac{d}{d x} (\frac{144}{5 x^{\frac{1}{5}}}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.2.8

Multiply $\frac{14}{5}$ by $\frac{9 x^{\frac{4}{5}}}{5}$ .

$f'' (x) = \frac{14 (9 x^{\frac{4}{5}})}{5 \cdot 5} + \frac{d}{d x} (\frac{144}{5 x^{\frac{1}{5}}}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.2.9

Multiply $9$ by $14$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{5 \cdot 5} + \frac{d}{d x} (\frac{144}{5 x^{\frac{1}{5}}}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.2.10

Multiply $5$ by $5$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{d}{d x} (\frac{144}{5 x^{\frac{1}{5}}}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3

Evaluate $\frac{d}{d x} [\frac{144}{5 x^{\frac{1}{5}}}]$ .

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Step 3.3.1

Since $\frac{144}{5}$ is constant with respect to $x$ , the derivative of $\frac{144}{5 x^{\frac{1}{5}}}$ with respect to $x$ is $\frac{144}{5} \frac{d}{d x} [\frac{1}{x^{\frac{1}{5}}}]$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot \frac{d}{d x} (\frac{1}{x^{\frac{1}{5}}}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.2

Rewrite $\frac{1}{x^{\frac{1}{5}}}$ as ${(x^{\frac{1}{5}})}^{- 1}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot \frac{d}{d x} ({(x^{\frac{1}{5}})}^{- 1}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.3

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = x^{- 1}$ and $g (x) = x^{\frac{1}{5}}$ .

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Step 3.3.3.1

To apply the Chain Rule, set $u$ as $x^{\frac{1}{5}}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (\frac{d}{d u} (u^{- 1}) \frac{d}{d x} (x^{\frac{1}{5}})) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.3.2

Differentiate using the Power Rule which states that $\frac{d}{d u} [u^{n}]$ is $n u^{n - 1}$ where $n = - 1$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- u^{- 2} \frac{d}{d x} x^{\frac{1}{5}}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.3.3

Replace all occurrences of $u$ with $x^{\frac{1}{5}}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- {(x^{\frac{1}{5}})}^{- 2} \frac{d}{d x} x^{\frac{1}{5}}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.4

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = \frac{1}{5}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- {(x^{\frac{1}{5}})}^{- 2} (\frac{1}{5} x^{\frac{1}{5} - 1})) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.5

Multiply the exponents in ${(x^{\frac{1}{5}})}^{- 2}$ .

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Step 3.3.5.1

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- x^{\frac{1}{5} \cdot - 2} (\frac{1}{5} x^{\frac{1}{5} - 1})) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.5.2

Combine $\frac{1}{5}$ and $- 2$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- x^{\frac{- 2}{5}} (\frac{1}{5} x^{\frac{1}{5} - 1})) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.5.3

Move the negative in front of the fraction.

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- x^{- \frac{2}{5}} (\frac{1}{5} x^{\frac{1}{5} - 1})) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.6

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- x^{- \frac{2}{5}} (\frac{1}{5} x^{\frac{1}{5} - 1 \cdot \frac{5}{5}})) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.7

Combine $- 1$ and $\frac{5}{5}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- x^{- \frac{2}{5}} (\frac{1}{5} x^{\frac{1}{5} + \frac{- 1 \cdot 5}{5}})) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.8

Combine the numerators over the common denominator.

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- x^{- \frac{2}{5}} (\frac{1}{5} x^{\frac{1 - 1 \cdot 5}{5}})) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.9

Simplify the numerator.

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Step 3.3.9.1

Multiply $- 1$ by $5$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- x^{- \frac{2}{5}} (\frac{1}{5} x^{\frac{1 - 5}{5}})) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.9.2

Subtract $5$ from $1$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- x^{- \frac{2}{5}} (\frac{1}{5} x^{\frac{- 4}{5}})) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.10

Move the negative in front of the fraction.

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- x^{- \frac{2}{5}} (\frac{1}{5} x^{- \frac{4}{5}})) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.11

Combine $\frac{1}{5}$ and $x^{- \frac{4}{5}}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- x^{- \frac{2}{5}} \frac{x^{- \frac{4}{5}}}{5}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.12

Combine $\frac{x^{- \frac{4}{5}}}{5}$ and $x^{- \frac{2}{5}}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- \frac{x^{- \frac{4}{5}} x^{- \frac{2}{5}}}{5}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.13

Multiply $x^{- \frac{4}{5}}$ by $x^{- \frac{2}{5}}$ by adding the exponents.

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Step 3.3.13.1

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- \frac{x^{- \frac{4}{5} - \frac{2}{5}}}{5}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.13.2

Combine the numerators over the common denominator.

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- \frac{x^{\frac{- 4 - 2}{5}}}{5}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.13.3

Subtract $2$ from $- 4$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- \frac{x^{\frac{- 6}{5}}}{5}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.13.4

Move the negative in front of the fraction.

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- \frac{x^{- \frac{6}{5}}}{5}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.14

Move $x^{- \frac{6}{5}}$ to the denominator using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} + \frac{144}{5} \cdot (- \frac{1}{5 x^{\frac{6}{5}}}) + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.15

Multiply $\frac{144}{5}$ by $\frac{1}{5 x^{\frac{6}{5}}}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} - \frac{144}{5 (5 x^{\frac{6}{5}})} + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.3.16

Multiply $5$ by $5$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} - \frac{144}{25 x^{\frac{6}{5}}} + \frac{d}{d x} (- \frac{108 x^{\frac{4}{5}}}{5})$

Step 3.4

Evaluate $\frac{d}{d x} [- \frac{108 x^{\frac{4}{5}}}{5}]$ .

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Step 3.4.1

Since $- \frac{108}{5}$ is constant with respect to $x$ , the derivative of $- \frac{108 x^{\frac{4}{5}}}{5}$ with respect to $x$ is $- \frac{108}{5} \frac{d}{d x} [x^{\frac{4}{5}}]$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} - \frac{144}{25 x^{\frac{6}{5}}} - \frac{108}{5} \cdot \frac{d}{d x} x^{\frac{4}{5}}$

Step 3.4.2

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = \frac{4}{5}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} - \frac{144}{25 x^{\frac{6}{5}}} - \frac{108}{5} \cdot (\frac{4}{5} x^{\frac{4}{5} - 1})$

Step 3.4.3

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} - \frac{144}{25 x^{\frac{6}{5}}} - \frac{108}{5} \cdot (\frac{4}{5} x^{\frac{4}{5} - 1 \cdot \frac{5}{5}})$

Step 3.4.4

Combine $- 1$ and $\frac{5}{5}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} - \frac{144}{25 x^{\frac{6}{5}}} - \frac{108}{5} \cdot (\frac{4}{5} x^{\frac{4}{5} + \frac{- 1 \cdot 5}{5}})$

Step 3.4.5

Combine the numerators over the common denominator.

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} - \frac{144}{25 x^{\frac{6}{5}}} - \frac{108}{5} \cdot (\frac{4}{5} x^{\frac{4 - 1 \cdot 5}{5}})$

Step 3.4.6

Simplify the numerator.

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Step 3.4.6.1

Multiply $- 1$ by $5$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} - \frac{144}{25 x^{\frac{6}{5}}} - \frac{108}{5} \cdot (\frac{4}{5} x^{\frac{4 - 5}{5}})$

Step 3.4.6.2

Subtract $5$ from $4$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} - \frac{144}{25 x^{\frac{6}{5}}} - \frac{108}{5} \cdot (\frac{4}{5} x^{\frac{- 1}{5}})$

Step 3.4.7

Move the negative in front of the fraction.

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} - \frac{144}{25 x^{\frac{6}{5}}} - \frac{108}{5} \cdot (\frac{4}{5} x^{- \frac{1}{5}})$

Step 3.4.8

Combine $\frac{4}{5}$ and $x^{- \frac{1}{5}}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} - \frac{144}{25 x^{\frac{6}{5}}} - \frac{108}{5} \cdot \frac{4 x^{- \frac{1}{5}}}{5}$

Step 3.4.9

Multiply $\frac{4 x^{- \frac{1}{5}}}{5}$ by $\frac{108}{5}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} - \frac{144}{25 x^{\frac{6}{5}}} - \frac{4 x^{- \frac{1}{5}} \cdot 108}{5 \cdot 5}$

Step 3.4.10

Multiply $108$ by $4$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} - \frac{144}{25 x^{\frac{6}{5}}} - \frac{432 x^{- \frac{1}{5}}}{5 \cdot 5}$

Step 3.4.11

Multiply $5$ by $5$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} - \frac{144}{25 x^{\frac{6}{5}}} - \frac{432 x^{- \frac{1}{5}}}{25}$

Step 3.4.12

Move $x^{- \frac{1}{5}}$ to the denominator using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$f'' (x) = \frac{126 x^{\frac{4}{5}}}{25} - \frac{144}{25 x^{\frac{6}{5}}} - \frac{432}{25 x^{\frac{1}{5}}}$

Step 4

To find the local maximum and minimum values of the function, set the derivative equal to $0$ and solve.

$\frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}} - \frac{108 x^{\frac{4}{5}}}{5} = 0$

Step 5

Find the first derivative.

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Step 5.1

Find the first derivative.

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Step 5.1.1

Rewrite ${(x - 6)}^{2}$ as $(x - 6) (x - 6)$ .

$\frac{d}{d x} [x^{\frac{4}{5}} ((x - 6) (x - 6))]$

Step 5.1.2

Expand $(x - 6) (x - 6)$ using the FOIL Method.

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Step 5.1.2.1

Apply the distributive property.

$\frac{d}{d x} [x^{\frac{4}{5}} (x (x - 6) - 6 (x - 6))]$

Step 5.1.2.2

Apply the distributive property.

$\frac{d}{d x} [x^{\frac{4}{5}} (x \cdot x + x \cdot - 6 - 6 (x - 6))]$

Step 5.1.2.3

Apply the distributive property.

$\frac{d}{d x} [x^{\frac{4}{5}} (x \cdot x + x \cdot - 6 - 6 x - 6 \cdot - 6)]$

Step 5.1.3

Simplify and combine like terms.

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Step 5.1.3.1

Simplify each term.

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Step 5.1.3.1.1

Multiply $x$ by $x$ .

$\frac{d}{d x} [x^{\frac{4}{5}} (x^{2} + x \cdot - 6 - 6 x - 6 \cdot - 6)]$

Step 5.1.3.1.2

Move $- 6$ to the left of $x$ .

$\frac{d}{d x} [x^{\frac{4}{5}} (x^{2} - 6 \cdot x - 6 x - 6 \cdot - 6)]$

Step 5.1.3.1.3

Multiply $- 6$ by $- 6$ .

$\frac{d}{d x} [x^{\frac{4}{5}} (x^{2} - 6 x - 6 x + 36)]$

Step 5.1.3.2

Subtract $6 x$ from $- 6 x$ .

$\frac{d}{d x} [x^{\frac{4}{5}} (x^{2} - 12 x + 36)]$

Step 5.1.4

$x^{\frac{4}{5}} \frac{d}{d x} [x^{2} - 12 x + 36] + (x^{2} - 12 x + 36) \frac{d}{d x} [x^{\frac{4}{5}}]$

Step 5.1.5

Differentiate.

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Step 5.1.5.1

By the Sum Rule, the derivative of $x^{2} - 12 x + 36$ with respect to $x$ is $\frac{d}{d x} [x^{2}] + \frac{d}{d x} [- 12 x] + \frac{d}{d x} [36]$ .

$x^{\frac{4}{5}} (\frac{d}{d x} [x^{2}] + \frac{d}{d x} [- 12 x] + \frac{d}{d x} [36]) + (x^{2} - 12 x + 36) \frac{d}{d x} [x^{\frac{4}{5}}]$

Step 5.1.5.2

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$x^{\frac{4}{5}} (2 x + \frac{d}{d x} [- 12 x] + \frac{d}{d x} [36]) + (x^{2} - 12 x + 36) \frac{d}{d x} [x^{\frac{4}{5}}]$

Step 5.1.5.3

Since $- 12$ is constant with respect to $x$ , the derivative of $- 12 x$ with respect to $x$ is $- 12 \frac{d}{d x} [x]$ .

$x^{\frac{4}{5}} (2 x - 12 \frac{d}{d x} [x] + \frac{d}{d x} [36]) + (x^{2} - 12 x + 36) \frac{d}{d x} [x^{\frac{4}{5}}]$

Step 5.1.5.4

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 1$ .

$x^{\frac{4}{5}} (2 x - 12 \cdot 1 + \frac{d}{d x} [36]) + (x^{2} - 12 x + 36) \frac{d}{d x} [x^{\frac{4}{5}}]$

Step 5.1.5.5

Multiply $- 12$ by $1$ .

$x^{\frac{4}{5}} (2 x - 12 + \frac{d}{d x} [36]) + (x^{2} - 12 x + 36) \frac{d}{d x} [x^{\frac{4}{5}}]$

Step 5.1.5.6

Since $36$ is constant with respect to $x$ , the derivative of $36$ with respect to $x$ is $0$ .

$x^{\frac{4}{5}} (2 x - 12 + 0) + (x^{2} - 12 x + 36) \frac{d}{d x} [x^{\frac{4}{5}}]$

Step 5.1.5.7

Add $2 x - 12$ and $0$ .

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) \frac{d}{d x} [x^{\frac{4}{5}}]$

Step 5.1.5.8

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = \frac{4}{5}$ .

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) (\frac{4}{5} x^{\frac{4}{5} - 1})$

Step 5.1.6

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) (\frac{4}{5} x^{\frac{4}{5} - 1 \cdot \frac{5}{5}})$

Step 5.1.7

Combine $- 1$ and $\frac{5}{5}$ .

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) (\frac{4}{5} x^{\frac{4}{5} + \frac{- 1 \cdot 5}{5}})$

Step 5.1.8

Combine the numerators over the common denominator.

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) (\frac{4}{5} x^{\frac{4 - 1 \cdot 5}{5}})$

Step 5.1.9

Simplify the numerator.

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Step 5.1.9.1

Multiply $- 1$ by $5$ .

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) (\frac{4}{5} x^{\frac{4 - 5}{5}})$

Step 5.1.9.2

Subtract $5$ from $4$ .

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) (\frac{4}{5} x^{\frac{- 1}{5}})$

Step 5.1.10

Move the negative in front of the fraction.

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) (\frac{4}{5} x^{- \frac{1}{5}})$

Step 5.1.11

Combine $\frac{4}{5}$ and $x^{- \frac{1}{5}}$ .

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) \frac{4 x^{- \frac{1}{5}}}{5}$

Step 5.1.12

Move $x^{- \frac{1}{5}}$ to the denominator using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$x^{\frac{4}{5}} (2 x - 12) + (x^{2} - 12 x + 36) \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13

Simplify.

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Step 5.1.13.1

Apply the distributive property.

$x^{\frac{4}{5}} (2 x) + x^{\frac{4}{5}} \cdot - 12 + (x^{2} - 12 x + 36) \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.2

Apply the distributive property.

$x^{\frac{4}{5}} (2 x) + x^{\frac{4}{5}} \cdot - 12 + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3

Combine terms.

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Step 5.1.13.3.1

Multiply $x^{\frac{4}{5}}$ by $x$ by adding the exponents.

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Step 5.1.13.3.1.1

Move $x$ .

$x \cdot x^{\frac{4}{5}} \cdot 2 + x^{\frac{4}{5}} \cdot - 12 + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.1.2

Multiply $x$ by $x^{\frac{4}{5}}$ .

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Step 5.1.13.3.1.2.1

Raise $x$ to the power of $1$ .

$x^{1} x^{\frac{4}{5}} \cdot 2 + x^{\frac{4}{5}} \cdot - 12 + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.1.2.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$x^{1 + \frac{4}{5}} \cdot 2 + x^{\frac{4}{5}} \cdot - 12 + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.1.3

Write $1$ as a fraction with a common denominator.

$x^{\frac{5}{5} + \frac{4}{5}} \cdot 2 + x^{\frac{4}{5}} \cdot - 12 + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.1.4

Combine the numerators over the common denominator.

$x^{\frac{5 + 4}{5}} \cdot 2 + x^{\frac{4}{5}} \cdot - 12 + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.1.5

Add $5$ and $4$ .

$x^{\frac{9}{5}} \cdot 2 + x^{\frac{4}{5}} \cdot - 12 + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.2

Move $2$ to the left of $x^{\frac{9}{5}}$ .

$2 \cdot x^{\frac{9}{5}} + x^{\frac{4}{5}} \cdot - 12 + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.3

Move $- 12$ to the left of $x^{\frac{4}{5}}$ .

$2 x^{\frac{9}{5}} - 12 \cdot x^{\frac{4}{5}} + x^{2} \frac{4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.4

Combine $x^{2}$ and $\frac{4}{5 x^{\frac{1}{5}}}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{x^{2} \cdot 4}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.5

Move $4$ to the left of $x^{2}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 \cdot x^{2}}{5 x^{\frac{1}{5}}} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.6

Move $x^{\frac{1}{5}}$ to the numerator using the negative exponent rule $\frac{1}{b^{n}} = b^{- n}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{2} x^{- \frac{1}{5}}}{5} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.7

Multiply $x^{2}$ by $x^{- \frac{1}{5}}$ by adding the exponents.

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Step 5.1.13.3.7.1

Move $x^{- \frac{1}{5}}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 (x^{- \frac{1}{5}} x^{2})}{5} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.7.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{- \frac{1}{5} + 2}}{5} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.7.3

To write $2$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{- \frac{1}{5} + 2 \cdot \frac{5}{5}}}{5} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.7.4

Combine $2$ and $\frac{5}{5}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{- \frac{1}{5} + \frac{2 \cdot 5}{5}}}{5} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.7.5

Combine the numerators over the common denominator.

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{- 1 + 2 \cdot 5}{5}}}{5} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.7.6

Simplify the numerator.

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Step 5.1.13.3.7.6.1

Multiply $2$ by $5$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{- 1 + 10}{5}}}{5} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.7.6.2

Add $- 1$ and $10$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} - 12 x \frac{4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.8

Combine $- 12$ and $\frac{4}{5 x^{\frac{1}{5}}}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + x \frac{- 12 \cdot 4}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.9

Multiply $- 12$ by $4$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + x \frac{- 48}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.10

Combine $x$ and $\frac{- 48}{5 x^{\frac{1}{5}}}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{x \cdot - 48}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.11

Move $- 48$ to the left of $x$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{- 48 \cdot x}{5 x^{\frac{1}{5}}} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.12

Move $x^{\frac{1}{5}}$ to the numerator using the negative exponent rule $\frac{1}{b^{n}} = b^{- n}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{- 48 x \cdot x^{- \frac{1}{5}}}{5} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.13

Multiply $x$ by $x^{- \frac{1}{5}}$ by adding the exponents.

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Step 5.1.13.3.13.1

Move $x^{- \frac{1}{5}}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{- 48 (x^{- \frac{1}{5}} x)}{5} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.13.2

Multiply $x^{- \frac{1}{5}}$ by $x$ .

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Step 5.1.13.3.13.2.1

Raise $x$ to the power of $1$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{- 48 (x^{- \frac{1}{5}} x^{1})}{5} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.13.2.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{- 48 x^{- \frac{1}{5} + 1}}{5} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.13.3

Write $1$ as a fraction with a common denominator.

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{- 48 x^{- \frac{1}{5} + \frac{5}{5}}}{5} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.13.4

Combine the numerators over the common denominator.

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{- 48 x^{\frac{- 1 + 5}{5}}}{5} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.13.5

Add $- 1$ and $5$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} + \frac{- 48 x^{\frac{4}{5}}}{5} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.14

Move the negative in front of the fraction.

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} - \frac{48 x^{\frac{4}{5}}}{5} + 36 \frac{4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.15

Combine $36$ and $\frac{4}{5 x^{\frac{1}{5}}}$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{36 \cdot 4}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.16

Multiply $36$ by $4$ .

$2 x^{\frac{9}{5}} - 12 x^{\frac{4}{5}} + \frac{4 x^{\frac{9}{5}}}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.17

To write $2 x^{\frac{9}{5}}$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$- 12 x^{\frac{4}{5}} + 2 x^{\frac{9}{5}} \cdot \frac{5}{5} + \frac{4 x^{\frac{9}{5}}}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.18

Combine $2 x^{\frac{9}{5}}$ and $\frac{5}{5}$ .

$- 12 x^{\frac{4}{5}} + \frac{2 x^{\frac{9}{5}} \cdot 5}{5} + \frac{4 x^{\frac{9}{5}}}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.19

Combine the numerators over the common denominator.

$- 12 x^{\frac{4}{5}} + \frac{2 x^{\frac{9}{5}} \cdot 5 + 4 x^{\frac{9}{5}}}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.20

Multiply $5$ by $2$ .

$- 12 x^{\frac{4}{5}} + \frac{10 x^{\frac{9}{5}} + 4 x^{\frac{9}{5}}}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.21

Add $10 x^{\frac{9}{5}}$ and $4 x^{\frac{9}{5}}$ .

$- 12 x^{\frac{4}{5}} + \frac{14 x^{\frac{9}{5}}}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.22

To write $- 12 x^{\frac{4}{5}}$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$- 12 x^{\frac{4}{5}} \cdot \frac{5}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.23

Combine $- 12 x^{\frac{4}{5}}$ and $\frac{5}{5}$ .

$\frac{- 12 x^{\frac{4}{5}} \cdot 5}{5} - \frac{48 x^{\frac{4}{5}}}{5} + \frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.24

Combine the numerators over the common denominator.

$\frac{- 12 x^{\frac{4}{5}} \cdot 5 - 48 x^{\frac{4}{5}}}{5} + \frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.25

Multiply $5$ by $- 12$ .

$\frac{- 60 x^{\frac{4}{5}} - 48 x^{\frac{4}{5}}}{5} + \frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.26

Subtract $48 x^{\frac{4}{5}}$ from $- 60 x^{\frac{4}{5}}$ .

$\frac{- 108 x^{\frac{4}{5}}}{5} + \frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 5.1.13.3.27

Move the negative in front of the fraction.

$- \frac{108 x^{\frac{4}{5}}}{5} + \frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}}$

Step 5.1.13.4

Reorder terms.

$f' (x) = \frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}} - \frac{108 x^{\frac{4}{5}}}{5}$

Step 5.2

The first derivative of $f (x)$ with respect to $x$ is $\frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}} - \frac{108 x^{\frac{4}{5}}}{5}$ .

$\frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}} - \frac{108 x^{\frac{4}{5}}}{5}$

Step 6

Set the first derivative equal to $0$ then solve the equation $\frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}} - \frac{108 x^{\frac{4}{5}}}{5} = 0$ .

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Step 6.1

Set the first derivative equal to $0$ .

$\frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}} - \frac{108 x^{\frac{4}{5}}}{5} = 0$

Step 6.2

Find the LCD of the terms in the equation.

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Step 6.2.1

Finding the LCD of a list of values is the same as finding the LCM of the denominators of those values.

$5, 5 x^{\frac{1}{5}}, 5, 1$

Step 6.2.2

Since $5, 5 x^{\frac{1}{5}}, 5, 1$ contains both numbers and variables, there are two steps to find the LCM. Find LCM for the numeric part $5, 5, 5, 1$ then find LCM for the variable part $x^{\frac{1}{5}}$ .

Step 6.2.3

The LCM is the smallest positive number that all of the numbers divide into evenly.

1. List the prime factors of each number.

2. Multiply each factor the greatest number of times it occurs in either number.

Step 6.2.4

Since $5$ has no factors besides $1$ and $5$ .

$5$ is a prime number

Step 6.2.5

The number $1$ is not a prime number because it only has one positive factor, which is itself.

Not prime

Step 6.2.6

The LCM of $5, 5, 5, 1$ is the result of multiplying all prime factors the greatest number of times they occur in either number.

$5$

Step 6.2.7

The LCM of $x^{\frac{1}{5}}$ is the result of multiplying all prime factors the greatest number of times they occur in either term.

$x^{\frac{1}{5}}$

Step 6.2.8

The LCM for $5, 5 x^{\frac{1}{5}}, 5, 1$ is the numeric part $5$ multiplied by the variable part.

$5 x^{\frac{1}{5}}$

Step 6.3

Multiply each term in $\frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}} - \frac{108 x^{\frac{4}{5}}}{5} = 0$ by $5 x^{\frac{1}{5}}$ to eliminate the fractions.

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Step 6.3.1

Multiply each term in $\frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}} - \frac{108 x^{\frac{4}{5}}}{5} = 0$ by $5 x^{\frac{1}{5}}$ .

$\frac{14 x^{\frac{9}{5}}}{5} (5 x^{\frac{1}{5}}) + \frac{144}{5 x^{\frac{1}{5}}} (5 x^{\frac{1}{5}}) - \frac{108 x^{\frac{4}{5}}}{5} (5 x^{\frac{1}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2

Simplify the left side.

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Step 6.3.2.1

Simplify each term.

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Step 6.3.2.1.1

Rewrite using the commutative property of multiplication.

$5 \frac{14 x^{\frac{9}{5}}}{5} x^{\frac{1}{5}} + \frac{144}{5 x^{\frac{1}{5}}} (5 x^{\frac{1}{5}}) - \frac{108 x^{\frac{4}{5}}}{5} (5 x^{\frac{1}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.2

Cancel the common factor of $5$ .

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Step 6.3.2.1.2.1

Cancel the common factor.

$5 \frac{14 x^{\frac{9}{5}}}{5} x^{\frac{1}{5}} + \frac{144}{5 x^{\frac{1}{5}}} (5 x^{\frac{1}{5}}) - \frac{108 x^{\frac{4}{5}}}{5} (5 x^{\frac{1}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.2.2

Rewrite the expression.

$14 x^{\frac{9}{5}} x^{\frac{1}{5}} + \frac{144}{5 x^{\frac{1}{5}}} (5 x^{\frac{1}{5}}) - \frac{108 x^{\frac{4}{5}}}{5} (5 x^{\frac{1}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.3

Multiply $x^{\frac{9}{5}}$ by $x^{\frac{1}{5}}$ by adding the exponents.

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Step 6.3.2.1.3.1

Move $x^{\frac{1}{5}}$ .

$14 (x^{\frac{1}{5}} x^{\frac{9}{5}}) + \frac{144}{5 x^{\frac{1}{5}}} (5 x^{\frac{1}{5}}) - \frac{108 x^{\frac{4}{5}}}{5} (5 x^{\frac{1}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.3.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$14 x^{\frac{1}{5} + \frac{9}{5}} + \frac{144}{5 x^{\frac{1}{5}}} (5 x^{\frac{1}{5}}) - \frac{108 x^{\frac{4}{5}}}{5} (5 x^{\frac{1}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.3.3

Combine the numerators over the common denominator.

$14 x^{\frac{1 + 9}{5}} + \frac{144}{5 x^{\frac{1}{5}}} (5 x^{\frac{1}{5}}) - \frac{108 x^{\frac{4}{5}}}{5} (5 x^{\frac{1}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.3.4

Add $1$ and $9$ .

$14 x^{\frac{10}{5}} + \frac{144}{5 x^{\frac{1}{5}}} (5 x^{\frac{1}{5}}) - \frac{108 x^{\frac{4}{5}}}{5} (5 x^{\frac{1}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.3.5

Divide $10$ by $5$ .

$14 x^{2} + \frac{144}{5 x^{\frac{1}{5}}} (5 x^{\frac{1}{5}}) - \frac{108 x^{\frac{4}{5}}}{5} (5 x^{\frac{1}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.4

Rewrite using the commutative property of multiplication.

$14 x^{2} + 5 \frac{144}{5 x^{\frac{1}{5}}} x^{\frac{1}{5}} - \frac{108 x^{\frac{4}{5}}}{5} (5 x^{\frac{1}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.5

Cancel the common factor of $5$ .

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Step 6.3.2.1.5.1

Cancel the common factor.

$14 x^{2} + 5 \frac{144}{5 x^{\frac{1}{5}}} x^{\frac{1}{5}} - \frac{108 x^{\frac{4}{5}}}{5} (5 x^{\frac{1}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.5.2

Rewrite the expression.

$14 x^{2} + \frac{144}{x^{\frac{1}{5}}} x^{\frac{1}{5}} - \frac{108 x^{\frac{4}{5}}}{5} (5 x^{\frac{1}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.6

Cancel the common factor of $x^{\frac{1}{5}}$ .

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Step 6.3.2.1.6.1

Cancel the common factor.

$14 x^{2} + \frac{144}{x^{\frac{1}{5}}} x^{\frac{1}{5}} - \frac{108 x^{\frac{4}{5}}}{5} (5 x^{\frac{1}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.6.2

Rewrite the expression.

$14 x^{2} + 144 - \frac{108 x^{\frac{4}{5}}}{5} (5 x^{\frac{1}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.7

Cancel the common factor of $5$ .

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Step 6.3.2.1.7.1

Move the leading negative in $- \frac{108 x^{\frac{4}{5}}}{5}$ into the numerator.

$14 x^{2} + 144 + \frac{- 108 x^{\frac{4}{5}}}{5} (5 x^{\frac{1}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.7.2

Factor $5$ out of $5 x^{\frac{1}{5}}$ .

$14 x^{2} + 144 + \frac{- 108 x^{\frac{4}{5}}}{5} (5 (x^{\frac{1}{5}})) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.7.3

Cancel the common factor.

$14 x^{2} + 144 + \frac{- 108 x^{\frac{4}{5}}}{5} (5 x^{\frac{1}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.7.4

Rewrite the expression.

$14 x^{2} + 144 - 108 x^{\frac{4}{5}} x^{\frac{1}{5}} = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.8

Multiply $x^{\frac{4}{5}}$ by $x^{\frac{1}{5}}$ by adding the exponents.

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Step 6.3.2.1.8.1

Move $x^{\frac{1}{5}}$ .

$14 x^{2} + 144 - 108 (x^{\frac{1}{5}} x^{\frac{4}{5}}) = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.8.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$14 x^{2} + 144 - 108 x^{\frac{1}{5} + \frac{4}{5}} = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.8.3

Combine the numerators over the common denominator.

$14 x^{2} + 144 - 108 x^{\frac{1 + 4}{5}} = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.8.4

Add $1$ and $4$ .

$14 x^{2} + 144 - 108 x^{\frac{5}{5}} = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.8.5

Divide $5$ by $5$ .

$14 x^{2} + 144 - 108 x^{1} = 0 (5 x^{\frac{1}{5}})$

Step 6.3.2.1.9

Simplify $- 108 x^{1}$ .

$14 x^{2} + 144 - 108 x = 0 (5 x^{\frac{1}{5}})$

Step 6.3.3

Simplify the right side.

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Step 6.3.3.1

Multiply $0 (5 x^{\frac{1}{5}})$ .

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Step 6.3.3.1.1

Multiply $5$ by $0$ .

$14 x^{2} + 144 - 108 x = 0 x^{\frac{1}{5}}$

Step 6.3.3.1.2

Multiply $0$ by $x^{\frac{1}{5}}$ .

$14 x^{2} + 144 - 108 x = 0$

Step 6.4

Solve the equation.

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Step 6.4.1

Factor the left side of the equation.

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Step 6.4.1.1

Factor $2$ out of $14 x^{2} + 144 - 108 x$ .

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Step 6.4.1.1.1

Factor $2$ out of $14 x^{2}$ .

$2 (7 x^{2}) + 144 - 108 x = 0$

Step 6.4.1.1.2

Factor $2$ out of $144$ .

$2 (7 x^{2}) + 2 (72) - 108 x = 0$

Step 6.4.1.1.3

Factor $2$ out of $- 108 x$ .

$2 (7 x^{2}) + 2 (72) + 2 (- 54 x) = 0$

Step 6.4.1.1.4

Factor $2$ out of $2 (7 x^{2}) + 2 (72)$ .

$2 (7 x^{2} + 72) + 2 (- 54 x) = 0$

Step 6.4.1.1.5

Factor $2$ out of $2 (7 x^{2} + 72) + 2 (- 54 x)$ .

$2 (7 x^{2} + 72 - 54 x) = 0$

Step 6.4.1.2

Factor.

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Step 6.4.1.2.1

Factor by grouping.

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Step 6.4.1.2.1.1

Reorder terms.

$2 (7 x^{2} - 54 x + 72) = 0$

Step 6.4.1.2.1.2

For a polynomial of the form $a x^{2} + b x + c$ , rewrite the middle term as a sum of two terms whose product is $a \cdot c = 7 \cdot 72 = 504$ and whose sum is $b = - 54$ .

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Step 6.4.1.2.1.2.1

Factor $- 54$ out of $- 54 x$ .

$2 (7 x^{2} - 54 x + 72) = 0$

Step 6.4.1.2.1.2.2

Rewrite $- 54$ as $- 12$ plus $- 42$

$2 (7 x^{2} + (- 12 - 42) x + 72) = 0$

Step 6.4.1.2.1.2.3

Apply the distributive property.

$2 (7 x^{2} - 12 x - 42 x + 72) = 0$

Step 6.4.1.2.1.3

Factor out the greatest common factor from each group.

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Step 6.4.1.2.1.3.1

Group the first two terms and the last two terms.

$2 ((7 x^{2} - 12 x) - 42 x + 72) = 0$

Step 6.4.1.2.1.3.2

Factor out the greatest common factor (GCF) from each group.

$2 (x (7 x - 12) - 6 (7 x - 12)) = 0$

Step 6.4.1.2.1.4

Factor the polynomial by factoring out the greatest common factor, $7 x - 12$ .

$2 ((7 x - 12) (x - 6)) = 0$

Step 6.4.1.2.2

Remove unnecessary parentheses.

$2 (7 x - 12) (x - 6) = 0$

Step 6.4.2

If any individual factor on the left side of the equation is equal to $0$ , the entire expression will be equal to $0$ .

$7 x - 12 = 0$

$x - 6 = 0$

Step 6.4.3

Set $7 x - 12$ equal to $0$ and solve for $x$ .

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Step 6.4.3.1

Set $7 x - 12$ equal to $0$ .

$7 x - 12 = 0$

Step 6.4.3.2

Solve $7 x - 12 = 0$ for $x$ .

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Step 6.4.3.2.1

Add $12$ to both sides of the equation.

$7 x = 12$

Step 6.4.3.2.2

Divide each term in $7 x = 12$ by $7$ and simplify.

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Step 6.4.3.2.2.1

Divide each term in $7 x = 12$ by $7$ .

$\frac{7 x}{7} = \frac{12}{7}$

Step 6.4.3.2.2.2

Simplify the left side.

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Step 6.4.3.2.2.2.1

Cancel the common factor of $7$ .

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Step 6.4.3.2.2.2.1.1

Cancel the common factor.

$\frac{7 x}{7} = \frac{12}{7}$

Step 6.4.3.2.2.2.1.2

Divide $x$ by $1$ .

$x = \frac{12}{7}$

Step 6.4.4

Set $x - 6$ equal to $0$ and solve for $x$ .

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Step 6.4.4.1

Set $x - 6$ equal to $0$ .

$x - 6 = 0$

Step 6.4.4.2

Add $6$ to both sides of the equation.

$x = 6$

Step 6.4.5

The final solution is all the values that make $2 (7 x - 12) (x - 6) = 0$ true.

$x = \frac{12}{7}, 6$

Step 7

Find the values where the derivative is undefined.

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Step 7.1

Convert expressions with fractional exponents to radicals.

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Step 7.1.1

Apply the rule $x^{\frac{m}{n}} = \sqrt[n]{x^{m}}$ to rewrite the exponentiation as a radical.

$\frac{14 \sqrt[5]{x^{9}}}{5} + \frac{144}{5 x^{\frac{1}{5}}} - \frac{108 x^{\frac{4}{5}}}{5}$

Step 7.1.2

Apply the rule $x^{\frac{m}{n}} = \sqrt[n]{x^{m}}$ to rewrite the exponentiation as a radical.

$\frac{14 \sqrt[5]{x^{9}}}{5} + \frac{144}{5 \sqrt[5]{x^{1}}} - \frac{108 x^{\frac{4}{5}}}{5}$

Step 7.1.3

Apply the rule $x^{\frac{m}{n}} = \sqrt[n]{x^{m}}$ to rewrite the exponentiation as a radical.

$\frac{14 \sqrt[5]{x^{9}}}{5} + \frac{144}{5 \sqrt[5]{x^{1}}} - \frac{108 \sqrt[5]{x^{4}}}{5}$

Step 7.1.4

Anything raised to $1$ is the base itself.

$\frac{14 \sqrt[5]{x^{9}}}{5} + \frac{144}{5 \sqrt[5]{x}} - \frac{108 \sqrt[5]{x^{4}}}{5}$

Step 7.2

Set the denominator in $\frac{144}{5 \sqrt[5]{x}}$ equal to $0$ to find where the expression is undefined.

$5 \sqrt[5]{x} = 0$

Step 7.3

Solve for $x$ .

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Step 7.3.1

To remove the radical on the left side of the equation, raise both sides of the equation to the power of $5$ .

${(5 \sqrt[5]{x})}^{5} = 0^{5}$

Step 7.3.2

Simplify each side of the equation.

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Step 7.3.2.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt[5]{x}$ as $x^{\frac{1}{5}}$ .

${(5 x^{\frac{1}{5}})}^{5} = 0^{5}$

Step 7.3.2.2

Simplify the left side.

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Step 7.3.2.2.1

Simplify ${(5 x^{\frac{1}{5}})}^{5}$ .

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Step 7.3.2.2.1.1

Apply the product rule to $5 x^{\frac{1}{5}}$ .

$5^{5} {(x^{\frac{1}{5}})}^{5} = 0^{5}$

Step 7.3.2.2.1.2

Raise $5$ to the power of $5$ .

$3125 {(x^{\frac{1}{5}})}^{5} = 0^{5}$

Step 7.3.2.2.1.3

Multiply the exponents in ${(x^{\frac{1}{5}})}^{5}$ .

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Step 7.3.2.2.1.3.1

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$3125 x^{\frac{1}{5} \cdot 5} = 0^{5}$

Step 7.3.2.2.1.3.2

Cancel the common factor of $5$ .

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Step 7.3.2.2.1.3.2.1

Cancel the common factor.

$3125 x^{\frac{1}{5} \cdot 5} = 0^{5}$

Step 7.3.2.2.1.3.2.2

Rewrite the expression.

$3125 x^{1} = 0^{5}$

Step 7.3.2.2.1.4

Simplify.

$3125 x = 0^{5}$

Step 7.3.2.3

Simplify the right side.

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Step 7.3.2.3.1

Raising $0$ to any positive power yields $0$ .

$3125 x = 0$

Step 7.3.3

Divide each term in $3125 x = 0$ by $3125$ and simplify.

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Step 7.3.3.1

Divide each term in $3125 x = 0$ by $3125$ .

$\frac{3125 x}{3125} = \frac{0}{3125}$

Step 7.3.3.2

Simplify the left side.

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Step 7.3.3.2.1

Cancel the common factor of $3125$ .

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Step 7.3.3.2.1.1

Cancel the common factor.

$\frac{3125 x}{3125} = \frac{0}{3125}$

Step 7.3.3.2.1.2

Divide $x$ by $1$ .

$x = \frac{0}{3125}$

Step 7.3.3.3

Simplify the right side.

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Step 7.3.3.3.1

Divide $0$ by $3125$ .

$x = 0$

Step 8

Critical points to evaluate.

$x = \frac{12}{7}, 6, 0$

Step 9

Evaluate the second derivative at $x = \frac{12}{7}$ . If the second derivative is positive, then this is a local minimum. If it is negative, then this is a local maximum.

$\frac{126 {(\frac{12}{7})}^{\frac{4}{5}}}{25} - \frac{144}{25 {(\frac{12}{7})}^{\frac{6}{5}}} - \frac{432}{25 {(\frac{12}{7})}^{\frac{1}{5}}}$

Step 10

Evaluate the second derivative.

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Step 10.1

Simplify each term.

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Step 10.1.1

Apply the product rule to $\frac{12}{7}$ .

$\frac{126 \frac{12^{\frac{4}{5}}}{7^{\frac{4}{5}}}}{25} - \frac{144}{25 {(\frac{12}{7})}^{\frac{6}{5}}} - \frac{432}{25 {(\frac{12}{7})}^{\frac{1}{5}}}$

Step 10.1.2

Combine $126$ and $\frac{12^{\frac{4}{5}}}{7^{\frac{4}{5}}}$ .

$\frac{\frac{126 \cdot 12^{\frac{4}{5}}}{7^{\frac{4}{5}}}}{25} - \frac{144}{25 {(\frac{12}{7})}^{\frac{6}{5}}} - \frac{432}{25 {(\frac{12}{7})}^{\frac{1}{5}}}$

Step 10.1.3

Multiply the numerator by the reciprocal of the denominator.

$\frac{126 \cdot 12^{\frac{4}{5}}}{7^{\frac{4}{5}}} \cdot \frac{1}{25} - \frac{144}{25 {(\frac{12}{7})}^{\frac{6}{5}}} - \frac{432}{25 {(\frac{12}{7})}^{\frac{1}{5}}}$

Step 10.1.4

Combine.

$\frac{126 \cdot 12^{\frac{4}{5}} \cdot 1}{7^{\frac{4}{5}} \cdot 25} - \frac{144}{25 {(\frac{12}{7})}^{\frac{6}{5}}} - \frac{432}{25 {(\frac{12}{7})}^{\frac{1}{5}}}$

Step 10.1.5

Multiply $126$ by $1$ .

$\frac{126 \cdot 12^{\frac{4}{5}}}{7^{\frac{4}{5}} \cdot 25} - \frac{144}{25 {(\frac{12}{7})}^{\frac{6}{5}}} - \frac{432}{25 {(\frac{12}{7})}^{\frac{1}{5}}}$

Step 10.1.6

Move $25$ to the left of $7^{\frac{4}{5}}$ .

$\frac{126 \cdot 12^{\frac{4}{5}}}{25 \cdot 7^{\frac{4}{5}}} - \frac{144}{25 {(\frac{12}{7})}^{\frac{6}{5}}} - \frac{432}{25 {(\frac{12}{7})}^{\frac{1}{5}}}$

Step 10.1.7

Apply the product rule to $\frac{12}{7}$ .

$\frac{126 \cdot 12^{\frac{4}{5}}}{25 \cdot 7^{\frac{4}{5}}} - \frac{144}{25 \frac{12^{\frac{6}{5}}}{7^{\frac{6}{5}}}} - \frac{432}{25 {(\frac{12}{7})}^{\frac{1}{5}}}$

Step 10.1.8

Combine $25$ and $\frac{12^{\frac{6}{5}}}{7^{\frac{6}{5}}}$ .

$\frac{126 \cdot 12^{\frac{4}{5}}}{25 \cdot 7^{\frac{4}{5}}} - \frac{144}{\frac{25 \cdot 12^{\frac{6}{5}}}{7^{\frac{6}{5}}}} - \frac{432}{25 {(\frac{12}{7})}^{\frac{1}{5}}}$

Step 10.1.9

Multiply the numerator by the reciprocal of the denominator.

$\frac{126 \cdot 12^{\frac{4}{5}}}{25 \cdot 7^{\frac{4}{5}}} - (144 \frac{7^{\frac{6}{5}}}{25 \cdot 12^{\frac{6}{5}}}) - \frac{432}{25 {(\frac{12}{7})}^{\frac{1}{5}}}$

Step 10.1.10

Combine $144$ and $\frac{7^{\frac{6}{5}}}{25 \cdot 12^{\frac{6}{5}}}$ .

$\frac{126 \cdot 12^{\frac{4}{5}}}{25 \cdot 7^{\frac{4}{5}}} - \frac{144 \cdot 7^{\frac{6}{5}}}{25 \cdot 12^{\frac{6}{5}}} - \frac{432}{25 {(\frac{12}{7})}^{\frac{1}{5}}}$

Step 10.1.11

Apply the product rule to $\frac{12}{7}$ .

$\frac{126 \cdot 12^{\frac{4}{5}}}{25 \cdot 7^{\frac{4}{5}}} - \frac{144 \cdot 7^{\frac{6}{5}}}{25 \cdot 12^{\frac{6}{5}}} - \frac{432}{25 \frac{12^{\frac{1}{5}}}{7^{\frac{1}{5}}}}$

Step 10.1.12

Combine $25$ and $\frac{12^{\frac{1}{5}}}{7^{\frac{1}{5}}}$ .

$\frac{126 \cdot 12^{\frac{4}{5}}}{25 \cdot 7^{\frac{4}{5}}} - \frac{144 \cdot 7^{\frac{6}{5}}}{25 \cdot 12^{\frac{6}{5}}} - \frac{432}{\frac{25 \cdot 12^{\frac{1}{5}}}{7^{\frac{1}{5}}}}$

Step 10.1.13

Multiply the numerator by the reciprocal of the denominator.

$\frac{126 \cdot 12^{\frac{4}{5}}}{25 \cdot 7^{\frac{4}{5}}} - \frac{144 \cdot 7^{\frac{6}{5}}}{25 \cdot 12^{\frac{6}{5}}} - (432 \frac{7^{\frac{1}{5}}}{25 \cdot 12^{\frac{1}{5}}})$

Step 10.1.14

Combine $432$ and $\frac{7^{\frac{1}{5}}}{25 \cdot 12^{\frac{1}{5}}}$ .

$\frac{126 \cdot 12^{\frac{4}{5}}}{25 \cdot 7^{\frac{4}{5}}} - \frac{144 \cdot 7^{\frac{6}{5}}}{25 \cdot 12^{\frac{6}{5}}} - \frac{432 \cdot 7^{\frac{1}{5}}}{25 \cdot 12^{\frac{1}{5}}}$

Step 10.2

To write $- \frac{432 \cdot 7^{\frac{1}{5}}}{25 \cdot 12^{\frac{1}{5}}}$ as a fraction with a common denominator, multiply by $\frac{12^{\frac{5}{5}}}{12^{\frac{5}{5}}}$ .

$\frac{126 \cdot 12^{\frac{4}{5}}}{25 \cdot 7^{\frac{4}{5}}} - \frac{144 \cdot 7^{\frac{6}{5}}}{25 \cdot 12^{\frac{6}{5}}} - \frac{432 \cdot 7^{\frac{1}{5}}}{25 \cdot 12^{\frac{1}{5}}} \cdot \frac{12^{\frac{5}{5}}}{12^{\frac{5}{5}}}$

Step 10.3

Write each expression with a common denominator of $25 \cdot 12^{\frac{6}{5}}$ , by multiplying each by an appropriate factor of $1$ .

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Step 10.3.1

Multiply $\frac{432 \cdot 7^{\frac{1}{5}}}{25 \cdot 12^{\frac{1}{5}}}$ by $\frac{12^{\frac{5}{5}}}{12^{\frac{5}{5}}}$ .

$\frac{126 \cdot 12^{\frac{4}{5}}}{25 \cdot 7^{\frac{4}{5}}} - \frac{144 \cdot 7^{\frac{6}{5}}}{25 \cdot 12^{\frac{6}{5}}} - \frac{432 \cdot 7^{\frac{1}{5}} \cdot 12^{\frac{5}{5}}}{25 \cdot 12^{\frac{1}{5}} \cdot 12^{\frac{5}{5}}}$

Step 10.3.2

Multiply $12^{\frac{1}{5}}$ by $12^{\frac{5}{5}}$ by adding the exponents.

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Step 10.3.2.1

Move $12^{\frac{5}{5}}$ .

Step 10.3.2.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

Step 10.3.2.3

Combine the numerators over the common denominator.

Step 10.3.2.4

Add $5$ and $1$ .

Step 10.4

Combine the numerators over the common denominator.

$\frac{126 \cdot 12^{\frac{4}{5}}}{25 \cdot 7^{\frac{4}{5}}} + \frac{- 144 \cdot 7^{\frac{6}{5}} - 432 \cdot 7^{\frac{1}{5}} \cdot 12^{\frac{5}{5}}}{25 \cdot 12^{\frac{6}{5}}}$

Step 10.5

Simplify each term.

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Step 10.5.1

Cancel the common factor of $5$ .

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Step 10.5.1.1

Cancel the common factor.

$\frac{126 \cdot 12^{\frac{4}{5}}}{25 \cdot 7^{\frac{4}{5}}} + \frac{- 144 \cdot 7^{\frac{6}{5}} - 432 \cdot 7^{\frac{1}{5}} \cdot 12^{\frac{5}{5}}}{25 \cdot 12^{\frac{6}{5}}}$

Step 10.5.1.2

Rewrite the expression.

$\frac{126 \cdot 12^{\frac{4}{5}}}{25 \cdot 7^{\frac{4}{5}}} + \frac{- 144 \cdot 7^{\frac{6}{5}} - 432 \cdot 7^{\frac{1}{5}} \cdot 12^{1}}{25 \cdot 12^{\frac{6}{5}}}$

Step 10.5.2

Simplify the numerator.

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Step 10.5.2.1

Evaluate the exponent.

$\frac{126 \cdot 12^{\frac{4}{5}}}{25 \cdot 7^{\frac{4}{5}}} + \frac{- 144 \cdot 7^{\frac{6}{5}} - 432 \cdot 7^{\frac{1}{5}} \cdot 12}{25 \cdot 12^{\frac{6}{5}}}$

Step 10.5.2.2

Multiply $12$ by $- 432$ .

$\frac{126 \cdot 12^{\frac{4}{5}}}{25 \cdot 7^{\frac{4}{5}}} + \frac{- 144 \cdot 7^{\frac{6}{5}} - 5184 \cdot 7^{\frac{1}{5}}}{25 \cdot 12^{\frac{6}{5}}}$

Step 11

$x = \frac{12}{7}$ is a local maximum because the value of the second derivative is negative. This is referred to as the second derivative test.

$x = \frac{12}{7}$ is a local maximum

Step 12

Find the y-value when $x = \frac{12}{7}$ .

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Step 12.1

Replace the variable $x$ with $\frac{12}{7}$ in the expression.

$f (\frac{12}{7}) = {(\frac{12}{7})}^{\frac{4}{5}} {((\frac{12}{7}) - 6)}^{2}$

Step 12.2

Simplify the result.

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Step 12.2.1

Apply the product rule to $\frac{12}{7}$ .

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}}}{7^{\frac{4}{5}}} \cdot {((\frac{12}{7}) - 6)}^{2}$

Step 12.2.2

To write $- 6$ as a fraction with a common denominator, multiply by $\frac{7}{7}$ .

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}}}{7^{\frac{4}{5}}} \cdot {(\frac{12}{7} - 6 \cdot \frac{7}{7})}^{2}$

Step 12.2.3

Combine $- 6$ and $\frac{7}{7}$ .

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}}}{7^{\frac{4}{5}}} \cdot {(\frac{12}{7} + \frac{- 6 \cdot 7}{7})}^{2}$

Step 12.2.4

Combine the numerators over the common denominator.

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}}}{7^{\frac{4}{5}}} \cdot {(\frac{12 - 6 \cdot 7}{7})}^{2}$

Step 12.2.5

Simplify the numerator.

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Step 12.2.5.1

Multiply $- 6$ by $7$ .

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}}}{7^{\frac{4}{5}}} \cdot {(\frac{12 - 42}{7})}^{2}$

Step 12.2.5.2

Subtract $42$ from $12$ .

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}}}{7^{\frac{4}{5}}} \cdot {(\frac{- 30}{7})}^{2}$

Step 12.2.6

Move the negative in front of the fraction.

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}}}{7^{\frac{4}{5}}} \cdot {(- \frac{30}{7})}^{2}$

Step 12.2.7

Use the power rule ${(a b)}^{n} = a^{n} b^{n}$ to distribute the exponent.

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Step 12.2.7.1

Apply the product rule to $- \frac{30}{7}$ .

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}}}{7^{\frac{4}{5}}} \cdot ({(- 1)}^{2} {(\frac{30}{7})}^{2})$

Step 12.2.7.2

Apply the product rule to $\frac{30}{7}$ .

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}}}{7^{\frac{4}{5}}} \cdot ({(- 1)}^{2} (\frac{30^{2}}{7^{2}}))$

Step 12.2.8

Simplify the expression.

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Step 12.2.8.1

Raise $- 1$ to the power of $2$ .

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}}}{7^{\frac{4}{5}}} \cdot (1 (\frac{30^{2}}{7^{2}}))$

Step 12.2.8.2

Multiply $\frac{30^{2}}{7^{2}}$ by $1$ .

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}}}{7^{\frac{4}{5}}} \cdot \frac{30^{2}}{7^{2}}$

Step 12.2.9

Combine.

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}} \cdot 30^{2}}{7^{\frac{4}{5}} \cdot 7^{2}}$

Step 12.2.10

Multiply $7^{\frac{4}{5}}$ by $7^{2}$ by adding the exponents.

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Step 12.2.10.1

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}} \cdot 30^{2}}{7^{\frac{4}{5} + 2}}$

Step 12.2.10.2

To write $2$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}} \cdot 30^{2}}{7^{\frac{4}{5} + 2 \cdot \frac{5}{5}}}$

Step 12.2.10.3

Combine $2$ and $\frac{5}{5}$ .

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}} \cdot 30^{2}}{7^{\frac{4}{5} + \frac{2 \cdot 5}{5}}}$

Step 12.2.10.4

Combine the numerators over the common denominator.

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}} \cdot 30^{2}}{7^{\frac{4 + 2 \cdot 5}{5}}}$

Step 12.2.10.5

Simplify the numerator.

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Step 12.2.10.5.1

Multiply $2$ by $5$ .

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}} \cdot 30^{2}}{7^{\frac{4 + 10}{5}}}$

Step 12.2.10.5.2

Add $4$ and $10$ .

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}} \cdot 30^{2}}{7^{\frac{14}{5}}}$

Step 12.2.11

Raise $30$ to the power of $2$ .

$f (\frac{12}{7}) = \frac{12^{\frac{4}{5}} \cdot 900}{7^{\frac{14}{5}}}$

Step 12.2.12

Move $900$ to the left of $12^{\frac{4}{5}}$ .

$f (\frac{12}{7}) = \frac{900 \cdot 12^{\frac{4}{5}}}{7^{\frac{14}{5}}}$

Step 12.2.13

The final answer is $\frac{900 \cdot 12^{\frac{4}{5}}}{7^{\frac{14}{5}}}$ .

$y = \frac{900 \cdot 12^{\frac{4}{5}}}{7^{\frac{14}{5}}}$

Step 13

Evaluate the second derivative at $x = 6$ . If the second derivative is positive, then this is a local minimum. If it is negative, then this is a local maximum.

$\frac{126 {(6)}^{\frac{4}{5}}}{25} - \frac{144}{25 {(6)}^{\frac{6}{5}}} - \frac{432}{25 {(6)}^{\frac{1}{5}}}$

Step 14

Evaluate the second derivative.

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Step 14.1

Remove parentheses.

$\frac{126 \cdot 6^{\frac{4}{5}}}{25} - \frac{144}{25 \cdot 6^{\frac{6}{5}}} - \frac{432}{25 \cdot 6^{\frac{1}{5}}}$

Step 14.2

To write $- \frac{432}{25 \cdot 6^{\frac{1}{5}}}$ as a fraction with a common denominator, multiply by $\frac{6^{\frac{5}{5}}}{6^{\frac{5}{5}}}$ .

$\frac{126 \cdot 6^{\frac{4}{5}}}{25} - \frac{144}{25 \cdot 6^{\frac{6}{5}}} - \frac{432}{25 \cdot 6^{\frac{1}{5}}} \cdot \frac{6^{\frac{5}{5}}}{6^{\frac{5}{5}}}$

Step 14.3

Write each expression with a common denominator of $25 \cdot 6^{\frac{6}{5}}$ , by multiplying each by an appropriate factor of $1$ .

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Step 14.3.1

Multiply $\frac{432}{25 \cdot 6^{\frac{1}{5}}}$ by $\frac{6^{\frac{5}{5}}}{6^{\frac{5}{5}}}$ .

$\frac{126 \cdot 6^{\frac{4}{5}}}{25} - \frac{144}{25 \cdot 6^{\frac{6}{5}}} - \frac{432 \cdot 6^{\frac{5}{5}}}{25 \cdot 6^{\frac{1}{5}} \cdot 6^{\frac{5}{5}}}$

Step 14.3.2

Multiply $6^{\frac{1}{5}}$ by $6^{\frac{5}{5}}$ by adding the exponents.

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Step 14.3.2.1

Move $6^{\frac{5}{5}}$ .

$\frac{126 \cdot 6^{\frac{4}{5}}}{25} - \frac{144}{25 \cdot 6^{\frac{6}{5}}} - \frac{432 \cdot 6^{\frac{5}{5}}}{25 \cdot (6^{\frac{5}{5}} \cdot 6^{\frac{1}{5}})}$

Step 14.3.2.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$\frac{126 \cdot 6^{\frac{4}{5}}}{25} - \frac{144}{25 \cdot 6^{\frac{6}{5}}} - \frac{432 \cdot 6^{\frac{5}{5}}}{25 \cdot 6^{\frac{5}{5} + \frac{1}{5}}}$

Step 14.3.2.3

Combine the numerators over the common denominator.

$\frac{126 \cdot 6^{\frac{4}{5}}}{25} - \frac{144}{25 \cdot 6^{\frac{6}{5}}} - \frac{432 \cdot 6^{\frac{5}{5}}}{25 \cdot 6^{\frac{5 + 1}{5}}}$

Step 14.3.2.4

Add $5$ and $1$ .

$\frac{126 \cdot 6^{\frac{4}{5}}}{25} - \frac{144}{25 \cdot 6^{\frac{6}{5}}} - \frac{432 \cdot 6^{\frac{5}{5}}}{25 \cdot 6^{\frac{6}{5}}}$

Step 14.4

Combine the numerators over the common denominator.

$\frac{126 \cdot 6^{\frac{4}{5}}}{25} + \frac{- 144 - 432 \cdot 6^{\frac{5}{5}}}{25 \cdot 6^{\frac{6}{5}}}$

Step 14.5

Simplify the numerator.

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Step 14.5.1

Divide $5$ by $5$ .

$\frac{126 \cdot 6^{\frac{4}{5}}}{25} + \frac{- 144 - 432 \cdot 6^{1}}{25 \cdot 6^{\frac{6}{5}}}$

Step 14.5.2

Raise $6$ to the power of $1$ .

$\frac{126 \cdot 6^{\frac{4}{5}}}{25} + \frac{- 144 - 432 \cdot 6}{25 \cdot 6^{\frac{6}{5}}}$

Step 14.5.3

Multiply $- 432$ by $6$ .

$\frac{126 \cdot 6^{\frac{4}{5}}}{25} + \frac{- 144 - 2592}{25 \cdot 6^{\frac{6}{5}}}$

Step 14.5.4

Subtract $2592$ from $- 144$ .

$\frac{126 \cdot 6^{\frac{4}{5}}}{25} + \frac{- 2736}{25 \cdot 6^{\frac{6}{5}}}$

Step 14.6

Move the negative in front of the fraction.

$\frac{126 \cdot 6^{\frac{4}{5}}}{25} - \frac{2736}{25 \cdot 6^{\frac{6}{5}}}$

Step 15

$x = 6$ is a local minimum because the value of the second derivative is positive. This is referred to as the second derivative test.

$x = 6$ is a local minimum

Step 16

Find the y-value when $x = 6$ .

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Step 16.1

Replace the variable $x$ with $6$ in the expression.

$f (6) = {(6)}^{\frac{4}{5}} {((6) - 6)}^{2}$

Step 16.2

Simplify the result.

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Step 16.2.1

Subtract $6$ from $6$ .

$f (6) = 6^{\frac{4}{5}} \cdot 0^{2}$

Step 16.2.2

Raising $0$ to any positive power yields $0$ .

$f (6) = 6^{\frac{4}{5}} \cdot 0$

Step 16.2.3

Multiply $6^{\frac{4}{5}}$ by $0$ .

$f (6) = 0$

Step 16.2.4

The final answer is $0$ .

$y = 0$

Step 17

Evaluate the second derivative at $x = 0$ . If the second derivative is positive, then this is a local minimum. If it is negative, then this is a local maximum.

$\frac{126 {(0)}^{\frac{4}{5}}}{25} - \frac{144}{25 {(0)}^{\frac{6}{5}}} - \frac{432}{25 {(0)}^{\frac{1}{5}}}$

Step 18

Evaluate the second derivative.

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Step 18.1

Simplify the expression.

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Step 18.1.1

Rewrite $0$ as $0^{5}$ .

$\frac{126 {(0)}^{\frac{4}{5}}}{25} - \frac{144}{25 {(0^{5})}^{\frac{6}{5}}} - \frac{432}{25 {(0)}^{\frac{1}{5}}}$

Step 18.1.2

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$\frac{126 {(0)}^{\frac{4}{5}}}{25} - \frac{144}{25 \cdot 0^{5 (\frac{6}{5})}} - \frac{432}{25 {(0)}^{\frac{1}{5}}}$

Step 18.2

Cancel the common factor of $5$ .

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Step 18.2.1

Cancel the common factor.

$\frac{126 {(0)}^{\frac{4}{5}}}{25} - \frac{144}{25 \cdot 0^{5 (\frac{6}{5})}} - \frac{432}{25 {(0)}^{\frac{1}{5}}}$

Step 18.2.2

Rewrite the expression.

$\frac{126 {(0)}^{\frac{4}{5}}}{25} - \frac{144}{25 \cdot 0^{6}} - \frac{432}{25 {(0)}^{\frac{1}{5}}}$

Step 18.3

Simplify the expression.

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Step 18.3.1

Raising $0$ to any positive power yields $0$ .

$\frac{126 {(0)}^{\frac{4}{5}}}{25} - \frac{144}{25 \cdot 0} - \frac{432}{25 {(0)}^{\frac{1}{5}}}$

Step 18.3.2

Multiply $25$ by $0$ .

$\frac{126 {(0)}^{\frac{4}{5}}}{25} - \frac{144}{0} - \frac{432}{25 {(0)}^{\frac{1}{5}}}$

Step 18.3.3

The expression contains a division by $0$ . The expression is undefined.

Undefined

$\frac{126 {(0)}^{\frac{4}{5}}}{25} - \frac{144}{0} - \frac{432}{25 {(0)}^{\frac{1}{5}}}$

Step 18.4

The expression contains a division by $0$ . The expression is undefined.

Undefined

Step 19

Since there is at least one point with $0$ or undefined second derivative, apply the first derivative test.

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Step 19.1

Split $(- \infty, \infty)$ into separate intervals around the $x$ values that make the first derivative $0$ or undefined.

$(- \infty, 0) \cup (0, \frac{12}{7}) \cup (\frac{12}{7}, 6) \cup (6, \infty)$

Step 19.2

Substitute any number, such as $- 2$ , from the interval $(- \infty, 0)$ in the first derivative $\frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}} - \frac{108 x^{\frac{4}{5}}}{5}$ to check if the result is negative or positive.

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Step 19.2.1

Replace the variable $x$ with $- 2$ in the expression.

$f' (- 2) = \frac{14 {(- 2)}^{\frac{9}{5}}}{5} + \frac{144}{5 {(- 2)}^{\frac{1}{5}}} - \frac{108 {(- 2)}^{\frac{4}{5}}}{5}$

Step 19.2.2

Simplify the result.

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Step 19.2.2.1

Combine the numerators over the common denominator.

$f' (- 2) = \frac{14 {(- 2)}^{\frac{9}{5}} - 108 {(- 2)}^{\frac{4}{5}}}{5} + \frac{144}{5 {(- 2)}^{\frac{1}{5}}}$

Step 19.2.2.2

The final answer is $\frac{14 {(- 2)}^{\frac{9}{5}} - 108 {(- 2)}^{\frac{4}{5}}}{5} + \frac{144}{5 {(- 2)}^{\frac{1}{5}}}$ .

$\frac{14 {(- 2)}^{\frac{9}{5}} - 108 {(- 2)}^{\frac{4}{5}}}{5} + \frac{144}{5 {(- 2)}^{\frac{1}{5}}}$

Step 19.3

Substitute any number, such as $1$ , from the interval $(0, \frac{12}{7})$ in the first derivative $\frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}} - \frac{108 x^{\frac{4}{5}}}{5}$ to check if the result is negative or positive.

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Step 19.3.1

Replace the variable $x$ with $1$ in the expression.

$f' (1) = \frac{14 {(1)}^{\frac{9}{5}}}{5} + \frac{144}{5 {(1)}^{\frac{1}{5}}} - \frac{108 {(1)}^{\frac{4}{5}}}{5}$

Step 19.3.2

Simplify the result.

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Step 19.3.2.1

Combine the numerators over the common denominator.

$f' (1) = \frac{14 {(1)}^{\frac{9}{5}} - 108 {(1)}^{\frac{4}{5}}}{5} + \frac{144}{5 {(1)}^{\frac{1}{5}}}$

Step 19.3.2.2

Simplify each term.

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Step 19.3.2.2.1

One to any power is one.

$f' (1) = \frac{14 \cdot 1 - 108 {(1)}^{\frac{4}{5}}}{5} + \frac{144}{5 {(1)}^{\frac{1}{5}}}$

Step 19.3.2.2.2

Multiply $14$ by $1$ .

$f' (1) = \frac{14 - 108 {(1)}^{\frac{4}{5}}}{5} + \frac{144}{5 {(1)}^{\frac{1}{5}}}$

Step 19.3.2.2.3

One to any power is one.

$f' (1) = \frac{14 - 108 \cdot 1}{5} + \frac{144}{5 {(1)}^{\frac{1}{5}}}$

Step 19.3.2.2.4

Multiply $- 108$ by $1$ .

$f' (1) = \frac{14 - 108}{5} + \frac{144}{5 {(1)}^{\frac{1}{5}}}$

Step 19.3.2.3

Subtract $108$ from $14$ .

$f' (1) = \frac{- 94}{5} + \frac{144}{5 {(1)}^{\frac{1}{5}}}$

Step 19.3.2.4

Simplify each term.

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Step 19.3.2.4.1

Move the negative in front of the fraction.

$f' (1) = - \frac{94}{5} + \frac{144}{5 {(1)}^{\frac{1}{5}}}$

Step 19.3.2.4.2

One to any power is one.

$f' (1) = - \frac{94}{5} + \frac{144}{5 \cdot 1}$

Step 19.3.2.4.3

Multiply $5$ by $1$ .

$f' (1) = - \frac{94}{5} + \frac{144}{5}$

Step 19.3.2.5

Combine fractions.

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Step 19.3.2.5.1

Combine the numerators over the common denominator.

$f' (1) = \frac{- 94 + 144}{5}$

Step 19.3.2.5.2

Simplify the expression.

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Step 19.3.2.5.2.1

Add $- 94$ and $144$ .

$f' (1) = \frac{50}{5}$

Step 19.3.2.5.2.2

Divide $50$ by $5$ .

$f' (1) = 10$

Step 19.3.2.6

The final answer is $10$ .

$10$

Step 19.4

Substitute any number, such as $4$ , from the interval $(\frac{12}{7}, 6)$ in the first derivative $\frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}} - \frac{108 x^{\frac{4}{5}}}{5}$ to check if the result is negative or positive.

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Step 19.4.1

Replace the variable $x$ with $4$ in the expression.

$f' (4) = \frac{14 {(4)}^{\frac{9}{5}}}{5} + \frac{144}{5 {(4)}^{\frac{1}{5}}} - \frac{108 {(4)}^{\frac{4}{5}}}{5}$

Step 19.4.2

Simplify the result.

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Step 19.4.2.1

Remove parentheses.

$f' (4) = \frac{14 \cdot 4^{\frac{9}{5}}}{5} + \frac{144}{5 \cdot 4^{\frac{1}{5}}} - \frac{108 \cdot 4^{\frac{4}{5}}}{5}$

Step 19.4.2.2

Combine the numerators over the common denominator.

$f' (4) = \frac{14 \cdot 4^{\frac{9}{5}} - 108 \cdot 4^{\frac{4}{5}}}{5} + \frac{144}{5 \cdot 4^{\frac{1}{5}}}$

Step 19.4.2.3

The final answer is $\frac{14 \cdot 4^{\frac{9}{5}} - 108 \cdot 4^{\frac{4}{5}}}{5} + \frac{144}{5 \cdot 4^{\frac{1}{5}}}$ .

$\frac{14 \cdot 4^{\frac{9}{5}} - 108 \cdot 4^{\frac{4}{5}}}{5} + \frac{144}{5 \cdot 4^{\frac{1}{5}}}$

Step 19.5

Substitute any number, such as $8$ , from the interval $(6, \infty)$ in the first derivative $\frac{14 x^{\frac{9}{5}}}{5} + \frac{144}{5 x^{\frac{1}{5}}} - \frac{108 x^{\frac{4}{5}}}{5}$ to check if the result is negative or positive.

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Step 19.5.1

Replace the variable $x$ with $8$ in the expression.

$f' (8) = \frac{14 {(8)}^{\frac{9}{5}}}{5} + \frac{144}{5 {(8)}^{\frac{1}{5}}} - \frac{108 {(8)}^{\frac{4}{5}}}{5}$

Step 19.5.2

Simplify the result.

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Step 19.5.2.1

Remove parentheses.

$f' (8) = \frac{14 \cdot 8^{\frac{9}{5}}}{5} + \frac{144}{5 \cdot 8^{\frac{1}{5}}} - \frac{108 \cdot 8^{\frac{4}{5}}}{5}$

Step 19.5.2.2

Combine the numerators over the common denominator.

$f' (8) = \frac{14 \cdot 8^{\frac{9}{5}} - 108 \cdot 8^{\frac{4}{5}}}{5} + \frac{144}{5 \cdot 8^{\frac{1}{5}}}$

Step 19.5.2.3

The final answer is $\frac{14 \cdot 8^{\frac{9}{5}} - 108 \cdot 8^{\frac{4}{5}}}{5} + \frac{144}{5 \cdot 8^{\frac{1}{5}}}$ .

$\frac{14 \cdot 8^{\frac{9}{5}} - 108 \cdot 8^{\frac{4}{5}}}{5} + \frac{144}{5 \cdot 8^{\frac{1}{5}}}$

Step 19.6

Since the first derivative changed signs from negative to positive around $x = 0$ , then $x = 0$ is a local minimum.

$x = 0$ is a local minimum

Step 19.7

Since the first derivative changed signs from positive to negative around $x = \frac{12}{7}$ , then $x = \frac{12}{7}$ is a local maximum.

$x = \frac{12}{7}$ is a local maximum

Step 19.8

Since the first derivative changed signs from negative to positive around $x = 6$ , then $x = 6$ is a local minimum.

$x = 6$ is a local minimum

Step 19.9

These are the local extrema for $f (x) = x^{\frac{4}{5}} {(x - 6)}^{2}$ .

$x = 0$ is a local minimum

$x = \frac{12}{7}$ is a local maximum

$x = 6$ is a local minimum

$x = 0$ is a local minimum

$x = \frac{12}{7}$ is a local maximum

$x = 6$ is a local minimum

Step 20