Calculus Examples

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

Step 1

Find the first derivative.

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Step 1.1

By the Sum Rule, the derivative of $6 x^{\frac{7}{2}} + 4 x^{\frac{5}{2}} + 2 x$ with respect to $x$ is $\frac{d}{d x} [6 x^{\frac{7}{2}}] + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$ .

$\frac{d}{d x} [6 x^{\frac{7}{2}}] + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.2

Evaluate $\frac{d}{d x} [6 x^{\frac{7}{2}}]$ .

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Step 1.2.1

Since $6$ is constant with respect to $x$ , the derivative of $6 x^{\frac{7}{2}}$ with respect to $x$ is $6 \frac{d}{d x} [x^{\frac{7}{2}}]$ .

$6 \frac{d}{d x} [x^{\frac{7}{2}}] + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.2.2

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = \frac{7}{2}$ .

$6 (\frac{7}{2} x^{\frac{7}{2} - 1}) + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.2.3

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{2}{2}$ .

$6 (\frac{7}{2} x^{\frac{7}{2} - 1 \cdot \frac{2}{2}}) + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.2.4

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

$6 (\frac{7}{2} x^{\frac{7}{2} + \frac{- 1 \cdot 2}{2}}) + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.2.5

Combine the numerators over the common denominator.

$6 (\frac{7}{2} x^{\frac{7 - 1 \cdot 2}{2}}) + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.2.6

Simplify the numerator.

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Step 1.2.6.1

Multiply $- 1$ by $2$ .

$6 (\frac{7}{2} x^{\frac{7 - 2}{2}}) + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.2.6.2

Subtract $2$ from $7$ .

$6 (\frac{7}{2} x^{\frac{5}{2}}) + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.2.7

Combine $\frac{7}{2}$ and $x^{\frac{5}{2}}$ .

$6 \frac{7 x^{\frac{5}{2}}}{2} + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.2.8

Combine $6$ and $\frac{7 x^{\frac{5}{2}}}{2}$ .

$\frac{6 (7 x^{\frac{5}{2}})}{2} + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.2.9

Multiply $7$ by $6$ .

$\frac{42 x^{\frac{5}{2}}}{2} + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.2.10

Factor $2$ out of $42 x^{\frac{5}{2}}$ .

$\frac{2 (21 x^{\frac{5}{2}})}{2} + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.2.11

Cancel the common factors.

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Step 1.2.11.1

Factor $2$ out of $2$ .

$\frac{2 (21 x^{\frac{5}{2}})}{2 (1)} + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.2.11.2

Cancel the common factor.

$\frac{2 (21 x^{\frac{5}{2}})}{2 \cdot 1} + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.2.11.3

Rewrite the expression.

$\frac{21 x^{\frac{5}{2}}}{1} + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.2.11.4

Divide $21 x^{\frac{5}{2}}$ by $1$ .

$21 x^{\frac{5}{2}} + \frac{d}{d x} [4 x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.3

Evaluate $\frac{d}{d x} [4 x^{\frac{5}{2}}]$ .

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Step 1.3.1

Since $4$ is constant with respect to $x$ , the derivative of $4 x^{\frac{5}{2}}$ with respect to $x$ is $4 \frac{d}{d x} [x^{\frac{5}{2}}]$ .

$21 x^{\frac{5}{2}} + 4 \frac{d}{d x} [x^{\frac{5}{2}}] + \frac{d}{d x} [2 x]$

Step 1.3.2

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = \frac{5}{2}$ .

$21 x^{\frac{5}{2}} + 4 (\frac{5}{2} x^{\frac{5}{2} - 1}) + \frac{d}{d x} [2 x]$

Step 1.3.3

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{2}{2}$ .

$21 x^{\frac{5}{2}} + 4 (\frac{5}{2} x^{\frac{5}{2} - 1 \cdot \frac{2}{2}}) + \frac{d}{d x} [2 x]$

Step 1.3.4

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

$21 x^{\frac{5}{2}} + 4 (\frac{5}{2} x^{\frac{5}{2} + \frac{- 1 \cdot 2}{2}}) + \frac{d}{d x} [2 x]$

Step 1.3.5

Combine the numerators over the common denominator.

$21 x^{\frac{5}{2}} + 4 (\frac{5}{2} x^{\frac{5 - 1 \cdot 2}{2}}) + \frac{d}{d x} [2 x]$

Step 1.3.6

Simplify the numerator.

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Step 1.3.6.1

Multiply $- 1$ by $2$ .

$21 x^{\frac{5}{2}} + 4 (\frac{5}{2} x^{\frac{5 - 2}{2}}) + \frac{d}{d x} [2 x]$

Step 1.3.6.2

Subtract $2$ from $5$ .

$21 x^{\frac{5}{2}} + 4 (\frac{5}{2} x^{\frac{3}{2}}) + \frac{d}{d x} [2 x]$

Step 1.3.7

Combine $\frac{5}{2}$ and $x^{\frac{3}{2}}$ .

$21 x^{\frac{5}{2}} + 4 \frac{5 x^{\frac{3}{2}}}{2} + \frac{d}{d x} [2 x]$

Step 1.3.8

Combine $4$ and $\frac{5 x^{\frac{3}{2}}}{2}$ .

$21 x^{\frac{5}{2}} + \frac{4 (5 x^{\frac{3}{2}})}{2} + \frac{d}{d x} [2 x]$

Step 1.3.9

Multiply $5$ by $4$ .

$21 x^{\frac{5}{2}} + \frac{20 x^{\frac{3}{2}}}{2} + \frac{d}{d x} [2 x]$

Step 1.3.10

Factor $2$ out of $20 x^{\frac{3}{2}}$ .

$21 x^{\frac{5}{2}} + \frac{2 (10 x^{\frac{3}{2}})}{2} + \frac{d}{d x} [2 x]$

Step 1.3.11

Cancel the common factors.

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Step 1.3.11.1

Factor $2$ out of $2$ .

$21 x^{\frac{5}{2}} + \frac{2 (10 x^{\frac{3}{2}})}{2 (1)} + \frac{d}{d x} [2 x]$

Step 1.3.11.2

Cancel the common factor.

$21 x^{\frac{5}{2}} + \frac{2 (10 x^{\frac{3}{2}})}{2 \cdot 1} + \frac{d}{d x} [2 x]$

Step 1.3.11.3

Rewrite the expression.

$21 x^{\frac{5}{2}} + \frac{10 x^{\frac{3}{2}}}{1} + \frac{d}{d x} [2 x]$

Step 1.3.11.4

Divide $10 x^{\frac{3}{2}}$ by $1$ .

$21 x^{\frac{5}{2}} + 10 x^{\frac{3}{2}} + \frac{d}{d x} [2 x]$

Step 1.4

Evaluate $\frac{d}{d x} [2 x]$ .

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Step 1.4.1

Since $2$ is constant with respect to $x$ , the derivative of $2 x$ with respect to $x$ is $2 \frac{d}{d x} [x]$ .

$21 x^{\frac{5}{2}} + 10 x^{\frac{3}{2}} + 2 \frac{d}{d x} [x]$

Step 1.4.2

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

$21 x^{\frac{5}{2}} + 10 x^{\frac{3}{2}} + 2 \cdot 1$

Step 1.4.3

Multiply $2$ by $1$ .

$f' (x) = 21 x^{\frac{5}{2}} + 10 x^{\frac{3}{2}} + 2$

Step 2

Find the second derivative.

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Step 2.1

By the Sum Rule, the derivative of $21 x^{\frac{5}{2}} + 10 x^{\frac{3}{2}} + 2$ with respect to $x$ is $\frac{d}{d x} [21 x^{\frac{5}{2}}] + \frac{d}{d x} [10 x^{\frac{3}{2}}] + \frac{d}{d x} [2]$ .

$\frac{d}{d x} [21 x^{\frac{5}{2}}] + \frac{d}{d x} [10 x^{\frac{3}{2}}] + \frac{d}{d x} [2]$

Step 2.2

Evaluate $\frac{d}{d x} [21 x^{\frac{5}{2}}]$ .

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Step 2.2.1

Since $21$ is constant with respect to $x$ , the derivative of $21 x^{\frac{5}{2}}$ with respect to $x$ is $21 \frac{d}{d x} [x^{\frac{5}{2}}]$ .

$21 \frac{d}{d x} [x^{\frac{5}{2}}] + \frac{d}{d x} [10 x^{\frac{3}{2}}] + \frac{d}{d x} [2]$

Step 2.2.2

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = \frac{5}{2}$ .

$21 (\frac{5}{2} x^{\frac{5}{2} - 1}) + \frac{d}{d x} [10 x^{\frac{3}{2}}] + \frac{d}{d x} [2]$

Step 2.2.3

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{2}{2}$ .

$21 (\frac{5}{2} x^{\frac{5}{2} - 1 \cdot \frac{2}{2}}) + \frac{d}{d x} [10 x^{\frac{3}{2}}] + \frac{d}{d x} [2]$

Step 2.2.4

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

$21 (\frac{5}{2} x^{\frac{5}{2} + \frac{- 1 \cdot 2}{2}}) + \frac{d}{d x} [10 x^{\frac{3}{2}}] + \frac{d}{d x} [2]$

Step 2.2.5

Combine the numerators over the common denominator.

$21 (\frac{5}{2} x^{\frac{5 - 1 \cdot 2}{2}}) + \frac{d}{d x} [10 x^{\frac{3}{2}}] + \frac{d}{d x} [2]$

Step 2.2.6

Simplify the numerator.

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Step 2.2.6.1

Multiply $- 1$ by $2$ .

$21 (\frac{5}{2} x^{\frac{5 - 2}{2}}) + \frac{d}{d x} [10 x^{\frac{3}{2}}] + \frac{d}{d x} [2]$

Step 2.2.6.2

Subtract $2$ from $5$ .

$21 (\frac{5}{2} x^{\frac{3}{2}}) + \frac{d}{d x} [10 x^{\frac{3}{2}}] + \frac{d}{d x} [2]$

Step 2.2.7

Combine $\frac{5}{2}$ and $x^{\frac{3}{2}}$ .

$21 \frac{5 x^{\frac{3}{2}}}{2} + \frac{d}{d x} [10 x^{\frac{3}{2}}] + \frac{d}{d x} [2]$

Step 2.2.8

Combine $21$ and $\frac{5 x^{\frac{3}{2}}}{2}$ .

$\frac{21 (5 x^{\frac{3}{2}})}{2} + \frac{d}{d x} [10 x^{\frac{3}{2}}] + \frac{d}{d x} [2]$

Step 2.2.9

Multiply $5$ by $21$ .

$\frac{105 x^{\frac{3}{2}}}{2} + \frac{d}{d x} [10 x^{\frac{3}{2}}] + \frac{d}{d x} [2]$

Step 2.3

Evaluate $\frac{d}{d x} [10 x^{\frac{3}{2}}]$ .

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Step 2.3.1

Since $10$ is constant with respect to $x$ , the derivative of $10 x^{\frac{3}{2}}$ with respect to $x$ is $10 \frac{d}{d x} [x^{\frac{3}{2}}]$ .

$\frac{105 x^{\frac{3}{2}}}{2} + 10 \frac{d}{d x} [x^{\frac{3}{2}}] + \frac{d}{d x} [2]$

Step 2.3.2

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = \frac{3}{2}$ .

$\frac{105 x^{\frac{3}{2}}}{2} + 10 (\frac{3}{2} x^{\frac{3}{2} - 1}) + \frac{d}{d x} [2]$

Step 2.3.3

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{2}{2}$ .

$\frac{105 x^{\frac{3}{2}}}{2} + 10 (\frac{3}{2} x^{\frac{3}{2} - 1 \cdot \frac{2}{2}}) + \frac{d}{d x} [2]$

Step 2.3.4

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

$\frac{105 x^{\frac{3}{2}}}{2} + 10 (\frac{3}{2} x^{\frac{3}{2} + \frac{- 1 \cdot 2}{2}}) + \frac{d}{d x} [2]$

Step 2.3.5

Combine the numerators over the common denominator.

$\frac{105 x^{\frac{3}{2}}}{2} + 10 (\frac{3}{2} x^{\frac{3 - 1 \cdot 2}{2}}) + \frac{d}{d x} [2]$

Step 2.3.6

Simplify the numerator.

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Step 2.3.6.1

Multiply $- 1$ by $2$ .

$\frac{105 x^{\frac{3}{2}}}{2} + 10 (\frac{3}{2} x^{\frac{3 - 2}{2}}) + \frac{d}{d x} [2]$

Step 2.3.6.2

Subtract $2$ from $3$ .

$\frac{105 x^{\frac{3}{2}}}{2} + 10 (\frac{3}{2} x^{\frac{1}{2}}) + \frac{d}{d x} [2]$

Step 2.3.7

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

$\frac{105 x^{\frac{3}{2}}}{2} + 10 \frac{3 x^{\frac{1}{2}}}{2} + \frac{d}{d x} [2]$

Step 2.3.8

Combine $10$ and $\frac{3 x^{\frac{1}{2}}}{2}$ .

$\frac{105 x^{\frac{3}{2}}}{2} + \frac{10 (3 x^{\frac{1}{2}})}{2} + \frac{d}{d x} [2]$

Step 2.3.9

Multiply $3$ by $10$ .

$\frac{105 x^{\frac{3}{2}}}{2} + \frac{30 x^{\frac{1}{2}}}{2} + \frac{d}{d x} [2]$

Step 2.3.10

Factor $2$ out of $30 x^{\frac{1}{2}}$ .

$\frac{105 x^{\frac{3}{2}}}{2} + \frac{2 (15 x^{\frac{1}{2}})}{2} + \frac{d}{d x} [2]$

Step 2.3.11

Cancel the common factors.

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Step 2.3.11.1

Factor $2$ out of $2$ .

$\frac{105 x^{\frac{3}{2}}}{2} + \frac{2 (15 x^{\frac{1}{2}})}{2 (1)} + \frac{d}{d x} [2]$

Step 2.3.11.2

Cancel the common factor.

$\frac{105 x^{\frac{3}{2}}}{2} + \frac{2 (15 x^{\frac{1}{2}})}{2 \cdot 1} + \frac{d}{d x} [2]$

Step 2.3.11.3

Rewrite the expression.

$\frac{105 x^{\frac{3}{2}}}{2} + \frac{15 x^{\frac{1}{2}}}{1} + \frac{d}{d x} [2]$

Step 2.3.11.4

Divide $15 x^{\frac{1}{2}}$ by $1$ .

$\frac{105 x^{\frac{3}{2}}}{2} + 15 x^{\frac{1}{2}} + \frac{d}{d x} [2]$

Step 2.4

Since $2$ is constant with respect to $x$ , the derivative of $2$ with respect to $x$ is $0$ .

$\frac{105 x^{\frac{3}{2}}}{2} + 15 x^{\frac{1}{2}} + 0$

Step 2.5

Simplify.

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Step 2.5.1

Add $\frac{105 x^{\frac{3}{2}}}{2} + 15 x^{\frac{1}{2}}$ and $0$ .

$\frac{105 x^{\frac{3}{2}}}{2} + 15 x^{\frac{1}{2}}$

Step 2.5.2

Reorder terms.

$f'' (x) = 15 x^{\frac{1}{2}} + \frac{105 x^{\frac{3}{2}}}{2}$

Step 3

The second derivative of $f (x)$ with respect to $x$ is $15 x^{\frac{1}{2}} + \frac{105 x^{\frac{3}{2}}}{2}$ .

$15 x^{\frac{1}{2}} + \frac{105 x^{\frac{3}{2}}}{2}$