Calculus Examples

$\frac{4}{x} - \frac{9}{\sqrt[3]{x}}$

Step 1

By the Sum Rule, the derivative of $\frac{4}{x} - \frac{9}{\sqrt[3]{x}}$ with respect to $x$ is $\frac{d}{d x} [\frac{4}{x}] + \frac{d}{d x} [- \frac{9}{\sqrt[3]{x}}]$ .

$\frac{d}{d x} [\frac{4}{x}] + \frac{d}{d x} [- \frac{9}{\sqrt[3]{x}}]$

Step 2

Evaluate $\frac{d}{d x} [\frac{4}{x}]$ .

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Step 2.1

Since $4$ is constant with respect to $x$ , the derivative of $\frac{4}{x}$ with respect to $x$ is $4 \frac{d}{d x} [\frac{1}{x}]$ .

$4 \frac{d}{d x} [\frac{1}{x}] + \frac{d}{d x} [- \frac{9}{\sqrt[3]{x}}]$

Step 2.2

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

$4 \frac{d}{d x} [x^{- 1}] + \frac{d}{d x} [- \frac{9}{\sqrt[3]{x}}]$

Step 2.3

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

$4 (- x^{- 2}) + \frac{d}{d x} [- \frac{9}{\sqrt[3]{x}}]$

Step 2.4

Multiply $- 1$ by $4$ .

$- 4 x^{- 2} + \frac{d}{d x} [- \frac{9}{\sqrt[3]{x}}]$

Step 3

Evaluate $\frac{d}{d x} [- \frac{9}{\sqrt[3]{x}}]$ .

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Step 3.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt[3]{x}$ as $x^{\frac{1}{3}}$ .

$- 4 x^{- 2} + \frac{d}{d x} [- \frac{9}{x^{\frac{1}{3}}}]$

Step 3.2

Since $- 9$ is constant with respect to $x$ , the derivative of $- \frac{9}{x^{\frac{1}{3}}}$ with respect to $x$ is $- 9 \frac{d}{d x} [\frac{1}{x^{\frac{1}{3}}}]$ .

$- 4 x^{- 2} - 9 \frac{d}{d x} [\frac{1}{x^{\frac{1}{3}}}]$

Step 3.3

Rewrite $\frac{1}{x^{\frac{1}{3}}}$ as ${(x^{\frac{1}{3}})}^{- 1}$ .

$- 4 x^{- 2} - 9 \frac{d}{d x} [{(x^{\frac{1}{3}})}^{- 1}]$

Step 3.4

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 $g (x) = x^{\frac{1}{3}}$ .

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Step 3.4.1

To apply the Chain Rule, set $u$ as $x^{\frac{1}{3}}$ .

$- 4 x^{- 2} - 9 (\frac{d}{d u} [u^{- 1}] \frac{d}{d x} [x^{\frac{1}{3}}])$

Step 3.4.2

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

$- 4 x^{- 2} - 9 (- u^{- 2} \frac{d}{d x} [x^{\frac{1}{3}}])$

Step 3.4.3

Replace all occurrences of $u$ with $x^{\frac{1}{3}}$ .

$- 4 x^{- 2} - 9 (- {(x^{\frac{1}{3}})}^{- 2} \frac{d}{d x} [x^{\frac{1}{3}}])$

Step 3.5

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = \frac{1}{3}$ .

$- 4 x^{- 2} - 9 (- {(x^{\frac{1}{3}})}^{- 2} (\frac{1}{3} x^{\frac{1}{3} - 1}))$

Step 3.6

Multiply the exponents in ${(x^{\frac{1}{3}})}^{- 2}$ .

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Step 3.6.1

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

$- 4 x^{- 2} - 9 (- x^{\frac{1}{3} \cdot - 2} (\frac{1}{3} x^{\frac{1}{3} - 1}))$

Step 3.6.2

Combine $\frac{1}{3}$ and $- 2$ .

$- 4 x^{- 2} - 9 (- x^{\frac{- 2}{3}} (\frac{1}{3} x^{\frac{1}{3} - 1}))$

Step 3.6.3

Move the negative in front of the fraction.

$- 4 x^{- 2} - 9 (- x^{- \frac{2}{3}} (\frac{1}{3} x^{\frac{1}{3} - 1}))$

Step 3.7

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{3}{3}$ .

$- 4 x^{- 2} - 9 (- x^{- \frac{2}{3}} (\frac{1}{3} x^{\frac{1}{3} - 1 \cdot \frac{3}{3}}))$

Step 3.8

Combine $- 1$ and $\frac{3}{3}$ .

$- 4 x^{- 2} - 9 (- x^{- \frac{2}{3}} (\frac{1}{3} x^{\frac{1}{3} + \frac{- 1 \cdot 3}{3}}))$

Step 3.9

Combine the numerators over the common denominator.

$- 4 x^{- 2} - 9 (- x^{- \frac{2}{3}} (\frac{1}{3} x^{\frac{1 - 1 \cdot 3}{3}}))$

Step 3.10

Simplify the numerator.

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Step 3.10.1

Multiply $- 1$ by $3$ .

$- 4 x^{- 2} - 9 (- x^{- \frac{2}{3}} (\frac{1}{3} x^{\frac{1 - 3}{3}}))$

Step 3.10.2

Subtract $3$ from $1$ .

$- 4 x^{- 2} - 9 (- x^{- \frac{2}{3}} (\frac{1}{3} x^{\frac{- 2}{3}}))$

Step 3.11

Move the negative in front of the fraction.

$- 4 x^{- 2} - 9 (- x^{- \frac{2}{3}} (\frac{1}{3} x^{- \frac{2}{3}}))$

Step 3.12

Combine $\frac{1}{3}$ and $x^{- \frac{2}{3}}$ .

$- 4 x^{- 2} - 9 (- x^{- \frac{2}{3}} \frac{x^{- \frac{2}{3}}}{3})$

Step 3.13

Combine $\frac{x^{- \frac{2}{3}}}{3}$ and $x^{- \frac{2}{3}}$ .

$- 4 x^{- 2} - 9 (- \frac{x^{- \frac{2}{3}} x^{- \frac{2}{3}}}{3})$

Step 3.14

Multiply $x^{- \frac{2}{3}}$ by $x^{- \frac{2}{3}}$ by adding the exponents.

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Step 3.14.1

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

$- 4 x^{- 2} - 9 (- \frac{x^{- \frac{2}{3} - \frac{2}{3}}}{3})$

Step 3.14.2

Combine the numerators over the common denominator.

$- 4 x^{- 2} - 9 (- \frac{x^{\frac{- 2 - 2}{3}}}{3})$

Step 3.14.3

Subtract $2$ from $- 2$ .

$- 4 x^{- 2} - 9 (- \frac{x^{\frac{- 4}{3}}}{3})$

Step 3.14.4

Move the negative in front of the fraction.

$- 4 x^{- 2} - 9 (- \frac{x^{- \frac{4}{3}}}{3})$

Step 3.15

Move $x^{- \frac{4}{3}}$ to the denominator using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$- 4 x^{- 2} - 9 (- \frac{1}{3 x^{\frac{4}{3}}})$

Step 3.16

Multiply $- 1$ by $- 9$ .

$- 4 x^{- 2} + 9 \frac{1}{3 x^{\frac{4}{3}}}$

Step 3.17

Combine $9$ and $\frac{1}{3 x^{\frac{4}{3}}}$ .

$- 4 x^{- 2} + \frac{9}{3 x^{\frac{4}{3}}}$

Step 3.18

Factor $3$ out of $9$ .

$- 4 x^{- 2} + \frac{3 \cdot 3}{3 x^{\frac{4}{3}}}$

Step 3.19

Cancel the common factors.

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Step 3.19.1

Factor $3$ out of $3 x^{\frac{4}{3}}$ .

$- 4 x^{- 2} + \frac{3 \cdot 3}{3 (x^{\frac{4}{3}})}$

Step 3.19.2

Cancel the common factor.

$- 4 x^{- 2} + \frac{3 \cdot 3}{3 x^{\frac{4}{3}}}$

Step 3.19.3

Rewrite the expression.

$- 4 x^{- 2} + \frac{3}{x^{\frac{4}{3}}}$

Step 4

Simplify.

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Step 4.1

Rewrite the expression using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$- 4 \frac{1}{x^{2}} + \frac{3}{x^{\frac{4}{3}}}$

Step 4.2

Combine terms.

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Step 4.2.1

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

$\frac{- 4}{x^{2}} + \frac{3}{x^{\frac{4}{3}}}$

Step 4.2.2

Move the negative in front of the fraction.

$- \frac{4}{x^{2}} + \frac{3}{x^{\frac{4}{3}}}$