Calculus Examples

$f (x) = {(x^{2} + 7)}^{7}$

Step 1

Find the first derivative.

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Step 1.1

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = x^{7}$ and $g (x) = x^{2} + 7$ .

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Step 1.1.1

To apply the Chain Rule, set $u$ as $x^{2} + 7$ .

$f' (x) = \frac{d}{d u} (u^{7}) \frac{d}{d x} (x^{2} + 7)$

Step 1.1.2

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

$f' (x) = 7 u^{6} \frac{d}{d x} (x^{2} + 7)$

Step 1.1.3

Replace all occurrences of $u$ with $x^{2} + 7$ .

$f' (x) = 7 {(x^{2} + 7)}^{6} \frac{d}{d x} (x^{2} + 7)$

Step 1.2

Differentiate.

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Step 1.2.1

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

$f' (x) = 7 {(x^{2} + 7)}^{6} (\frac{d}{d x} (x^{2}) + \frac{d}{d x} (7))$

Step 1.2.2

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

$f' (x) = 7 {(x^{2} + 7)}^{6} (2 x + \frac{d}{d x} (7))$

Step 1.2.3

Since $7$ is constant with respect to $x$ , the derivative of $7$ with respect to $x$ is $0$ .

$f' (x) = 7 {(x^{2} + 7)}^{6} (2 x + 0)$

Step 1.2.4

Simplify the expression.

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Step 1.2.4.1

Add $2 x$ and $0$ .

$f' (x) = 7 {(x^{2} + 7)}^{6} (2 x)$

Step 1.2.4.2

Multiply $2$ by $7$ .

$f' (x) = 14 {(x^{2} + 7)}^{6} x$

Step 1.2.4.3

Reorder the factors of $14 {(x^{2} + 7)}^{6} x$ .

$f' (x) = 14 x {(x^{2} + 7)}^{6}$

Step 2

Find the second derivative.

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Step 2.1

Since $14$ is constant with respect to $x$ , the derivative of $14 x {(x^{2} + 7)}^{6}$ with respect to $x$ is $14 \frac{d}{d x} [x {(x^{2} + 7)}^{6}]$ .

$f'' (x) = 14 \frac{d}{d x} (x {(x^{2} + 7)}^{6})$

Step 2.2

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 $f (x) = x$ and $g (x) = {(x^{2} + 7)}^{6}$ .

$f'' (x) = 14 (x \frac{d}{d x} ({(x^{2} + 7)}^{6}) + {(x^{2} + 7)}^{6} \frac{d}{d x} (x))$

Step 2.3

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = x^{6}$ and $g (x) = x^{2} + 7$ .

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Step 2.3.1

To apply the Chain Rule, set $u$ as $x^{2} + 7$ .

$f'' (x) = 14 (x (\frac{d}{d u} (u^{6}) \frac{d}{d x} (x^{2} + 7)) + {(x^{2} + 7)}^{6} \frac{d}{d x} (x))$

Step 2.3.2

Differentiate using the Power Rule which states that $\frac{d}{d u} [u^{n}]$ is $n u^{n - 1}$ where $n = 6$ .

$f'' (x) = 14 (x (6 u^{5} \frac{d}{d x} (x^{2} + 7)) + {(x^{2} + 7)}^{6} \frac{d}{d x} (x))$

Step 2.3.3

Replace all occurrences of $u$ with $x^{2} + 7$ .

$f'' (x) = 14 (x (6 {(x^{2} + 7)}^{5} \frac{d}{d x} (x^{2} + 7)) + {(x^{2} + 7)}^{6} \frac{d}{d x} (x))$

Step 2.4

Differentiate.

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Step 2.4.1

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

$f'' (x) = 14 (x (6 {(x^{2} + 7)}^{5} (\frac{d}{d x} (x^{2}) + \frac{d}{d x} (7))) + {(x^{2} + 7)}^{6} \frac{d}{d x} (x))$

Step 2.4.2

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

$f'' (x) = 14 (x (6 {(x^{2} + 7)}^{5} (2 x + \frac{d}{d x} (7))) + {(x^{2} + 7)}^{6} \frac{d}{d x} (x))$

Step 2.4.3

Since $7$ is constant with respect to $x$ , the derivative of $7$ with respect to $x$ is $0$ .

$f'' (x) = 14 (x (6 {(x^{2} + 7)}^{5} (2 x + 0)) + {(x^{2} + 7)}^{6} \frac{d}{d x} (x))$

Step 2.4.4

Simplify the expression.

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Step 2.4.4.1

Add $2 x$ and $0$ .

$f'' (x) = 14 (x (6 {(x^{2} + 7)}^{5} (2 x)) + {(x^{2} + 7)}^{6} \frac{d}{d x} (x))$

Step 2.4.4.2

Multiply $2$ by $6$ .

$f'' (x) = 14 (x (12 {(x^{2} + 7)}^{5} x) + {(x^{2} + 7)}^{6} \frac{d}{d x} (x))$

Step 2.5

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

$f'' (x) = 14 (x \cdot x (12 {(x^{2} + 7)}^{5}) + {(x^{2} + 7)}^{6} \frac{d}{d x} (x))$

Step 2.6

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

$f'' (x) = 14 (x \cdot x (12 {(x^{2} + 7)}^{5}) + {(x^{2} + 7)}^{6} \frac{d}{d x} (x))$

Step 2.7

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

$f'' (x) = 14 (x^{1 + 1} (12 {(x^{2} + 7)}^{5}) + {(x^{2} + 7)}^{6} \frac{d}{d x} (x))$

Step 2.8

Add $1$ and $1$ .

$f'' (x) = 14 (x^{2} (12 {(x^{2} + 7)}^{5}) + {(x^{2} + 7)}^{6} \frac{d}{d x} (x))$

Step 2.9

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

$f'' (x) = 14 (x^{2} (12 {(x^{2} + 7)}^{5}) + {(x^{2} + 7)}^{6} \cdot 1)$

Step 2.10

Multiply ${(x^{2} + 7)}^{6}$ by $1$ .

$f'' (x) = 14 (x^{2} (12 {(x^{2} + 7)}^{5}) + {(x^{2} + 7)}^{6})$

Step 2.11

Simplify.

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Step 2.11.1

Apply the distributive property.

$f'' (x) = 14 (x^{2} (12 {(x^{2} + 7)}^{5})) + 14 {(x^{2} + 7)}^{6}$

Step 2.11.2

Multiply $12$ by $14$ .

$f'' (x) = 168 (x^{2} ({(x^{2} + 7)}^{5})) + 14 {(x^{2} + 7)}^{6}$

Step 2.11.3

Factor $14 {(x^{2} + 7)}^{5}$ out of $168 x^{2} {(x^{2} + 7)}^{5} + 14 {(x^{2} + 7)}^{6}$ .

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Step 2.11.3.1

Factor $14 {(x^{2} + 7)}^{5}$ out of $168 x^{2} {(x^{2} + 7)}^{5}$ .

$f'' (x) = 14 {(x^{2} + 7)}^{5} (12 x^{2}) + 14 {(x^{2} + 7)}^{6}$

Step 2.11.3.2

Factor $14 {(x^{2} + 7)}^{5}$ out of $14 {(x^{2} + 7)}^{6}$ .

$f'' (x) = 14 {(x^{2} + 7)}^{5} (12 x^{2}) + 14 {(x^{2} + 7)}^{5} (x^{2} + 7)$

Step 2.11.3.3

Factor $14 {(x^{2} + 7)}^{5}$ out of $14 {(x^{2} + 7)}^{5} (12 x^{2}) + 14 {(x^{2} + 7)}^{5} (x^{2} + 7)$ .

$f'' (x) = 14 {(x^{2} + 7)}^{5} (12 x^{2} + x^{2} + 7)$

Step 2.11.4

Add $12 x^{2}$ and $x^{2}$ .

$f'' (x) = 14 {(x^{2} + 7)}^{5} (13 x^{2} + 7)$

Step 3

Find the third derivative.

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Step 3.1

Since $14$ is constant with respect to $x$ , the derivative of $14 {(x^{2} + 7)}^{5} (13 x^{2} + 7)$ with respect to $x$ is $14 \frac{d}{d x} [{(x^{2} + 7)}^{5} (13 x^{2} + 7)]$ .

$f''' (x) = 14 \frac{d}{d x} ({(x^{2} + 7)}^{5} (13 x^{2} + 7))$

Step 3.2

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 $f (x) = {(x^{2} + 7)}^{5}$ and $g (x) = 13 x^{2} + 7$ .

$f''' (x) = 14 ({(x^{2} + 7)}^{5} \frac{d}{d x} (13 x^{2} + 7) + (13 x^{2} + 7) \frac{d}{d x} ({(x^{2} + 7)}^{5}))$

Step 3.3

Differentiate.

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Step 3.3.1

By the Sum Rule, the derivative of $13 x^{2} + 7$ with respect to $x$ is $\frac{d}{d x} [13 x^{2}] + \frac{d}{d x} [7]$ .

$f''' (x) = 14 ({(x^{2} + 7)}^{5} (\frac{d}{d x} (13 x^{2}) + \frac{d}{d x} (7)) + (13 x^{2} + 7) \frac{d}{d x} ({(x^{2} + 7)}^{5}))$

Step 3.3.2

Since $13$ is constant with respect to $x$ , the derivative of $13 x^{2}$ with respect to $x$ is $13 \frac{d}{d x} [x^{2}]$ .

$f''' (x) = 14 ({(x^{2} + 7)}^{5} (13 \frac{d}{d x} (x^{2}) + \frac{d}{d x} (7)) + (13 x^{2} + 7) \frac{d}{d x} ({(x^{2} + 7)}^{5}))$

Step 3.3.3

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

$f''' (x) = 14 ({(x^{2} + 7)}^{5} (13 (2 x) + \frac{d}{d x} (7)) + (13 x^{2} + 7) \frac{d}{d x} ({(x^{2} + 7)}^{5}))$

Step 3.3.4

Multiply $2$ by $13$ .

$f''' (x) = 14 ({(x^{2} + 7)}^{5} (26 x + \frac{d}{d x} (7)) + (13 x^{2} + 7) \frac{d}{d x} ({(x^{2} + 7)}^{5}))$

Step 3.3.5

Since $7$ is constant with respect to $x$ , the derivative of $7$ with respect to $x$ is $0$ .

$f''' (x) = 14 ({(x^{2} + 7)}^{5} (26 x + 0) + (13 x^{2} + 7) \frac{d}{d x} ({(x^{2} + 7)}^{5}))$

Step 3.3.6

Simplify the expression.

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Step 3.3.6.1

Add $26 x$ and $0$ .

$f''' (x) = 14 ({(x^{2} + 7)}^{5} (26 x) + (13 x^{2} + 7) \frac{d}{d x} ({(x^{2} + 7)}^{5}))$

Step 3.3.6.2

Move $26$ to the left of ${(x^{2} + 7)}^{5}$ .

$f''' (x) = 14 (26 \cdot ({(x^{2} + 7)}^{5} x) + (13 x^{2} + 7) \frac{d}{d x} ({(x^{2} + 7)}^{5}))$

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 $f (x) = x^{5}$ and $g (x) = x^{2} + 7$ .

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Step 3.4.1

To apply the Chain Rule, set $u$ as $x^{2} + 7$ .

$f''' (x) = 14 (26 {(x^{2} + 7)}^{5} x + (13 x^{2} + 7) (\frac{d}{d u} (u^{5}) \frac{d}{d x} (x^{2} + 7)))$

Step 3.4.2

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

$f''' (x) = 14 (26 {(x^{2} + 7)}^{5} x + (13 x^{2} + 7) (5 u^{4} \frac{d}{d x} (x^{2} + 7)))$

Step 3.4.3

Replace all occurrences of $u$ with $x^{2} + 7$ .

$f''' (x) = 14 (26 {(x^{2} + 7)}^{5} x + (13 x^{2} + 7) (5 {(x^{2} + 7)}^{4} \frac{d}{d x} (x^{2} + 7)))$

Step 3.5

Differentiate.

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Step 3.5.1

Move $5$ to the left of $13 x^{2} + 7$ .

$f''' (x) = 14 (26 {(x^{2} + 7)}^{5} x + 5 \cdot ((13 x^{2} + 7) {(x^{2} + 7)}^{4}) \frac{d}{d x} (x^{2} + 7))$

Step 3.5.2

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

$f''' (x) = 14 (26 {(x^{2} + 7)}^{5} x + 5 (13 x^{2} + 7) {(x^{2} + 7)}^{4} (\frac{d}{d x} (x^{2}) + \frac{d}{d x} (7)))$

Step 3.5.3

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

$f''' (x) = 14 (26 {(x^{2} + 7)}^{5} x + 5 (13 x^{2} + 7) {(x^{2} + 7)}^{4} (2 x + \frac{d}{d x} (7)))$

Step 3.5.4

Since $7$ is constant with respect to $x$ , the derivative of $7$ with respect to $x$ is $0$ .

$f''' (x) = 14 (26 {(x^{2} + 7)}^{5} x + 5 (13 x^{2} + 7) {(x^{2} + 7)}^{4} (2 x + 0))$

Step 3.5.5

Simplify the expression.

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Step 3.5.5.1

Add $2 x$ and $0$ .

$f''' (x) = 14 (26 {(x^{2} + 7)}^{5} x + 5 (13 x^{2} + 7) {(x^{2} + 7)}^{4} (2 x))$

Step 3.5.5.2

Multiply $2$ by $5$ .

$f''' (x) = 14 (26 {(x^{2} + 7)}^{5} x + 10 (13 x^{2} + 7) {(x^{2} + 7)}^{4} x)$

Step 3.6

Simplify.

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Step 3.6.1

Apply the distributive property.

$f''' (x) = 14 (26 {(x^{2} + 7)}^{5} x + (10 (13 x^{2}) + 10 \cdot 7) {(x^{2} + 7)}^{4} x)$

Step 3.6.2

Apply the distributive property.

$f''' (x) = 14 (26 {(x^{2} + 7)}^{5} x) + 14 ((10 (13 x^{2}) + 10 \cdot 7) {(x^{2} + 7)}^{4} x)$

Step 3.6.3

Multiply $26$ by $14$ .

$f''' (x) = 364 ({(x^{2} + 7)}^{5} x) + 14 ((10 (13 x^{2}) + 10 \cdot 7) {(x^{2} + 7)}^{4} x)$

Step 3.6.4

Multiply $13$ by $10$ .

$f''' (x) = 364 {(x^{2} + 7)}^{5} x + 14 ((130 x^{2} + 10 \cdot 7) {(x^{2} + 7)}^{4} x)$

Step 3.6.5

Multiply $10$ by $7$ .

$f''' (x) = 364 {(x^{2} + 7)}^{5} x + 14 ((130 x^{2} + 70) {(x^{2} + 7)}^{4} x)$

Step 3.6.6

Factor $14 {(x^{2} + 7)}^{4} x$ out of $364 {(x^{2} + 7)}^{5} x + 14 (130 x^{2} + 70) {(x^{2} + 7)}^{4} x$ .

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Step 3.6.6.1

Factor $14 {(x^{2} + 7)}^{4} x$ out of $364 {(x^{2} + 7)}^{5} x$ .

$f''' (x) = 14 {(x^{2} + 7)}^{4} x (26 (x^{2} + 7)) + 14 (130 x^{2} + 70) {(x^{2} + 7)}^{4} x$

Step 3.6.6.2

Factor $14 {(x^{2} + 7)}^{4} x$ out of $14 (130 x^{2} + 70) {(x^{2} + 7)}^{4} x$ .

$f''' (x) = 14 {(x^{2} + 7)}^{4} x (26 (x^{2} + 7)) + 14 {(x^{2} + 7)}^{4} x (130 x^{2} + 70)$

Step 3.6.6.3

Factor $14 {(x^{2} + 7)}^{4} x$ out of $14 {(x^{2} + 7)}^{4} x (26 (x^{2} + 7)) + 14 {(x^{2} + 7)}^{4} x (130 x^{2} + 70)$ .

$f''' (x) = 14 {(x^{2} + 7)}^{4} x (26 (x^{2} + 7) + 130 x^{2} + 70)$

Step 3.6.7

Reorder the factors of $14 {(x^{2} + 7)}^{4} x (26 (x^{2} + 7) + 130 x^{2} + 70)$ .

$f''' (x) = 14 x {(x^{2} + 7)}^{4} (26 (x^{2} + 7) + 130 x^{2} + 70)$

Step 4

Find the fourth derivative.

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Step 4.1

Differentiate using the Constant Multiple Rule.

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Step 4.1.1

Simplify each term.

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Step 4.1.1.1

Apply the distributive property.

$f^{4} (x) = \frac{d}{d x} (14 x {(x^{2} + 7)}^{4} (26 x^{2} + 26 \cdot 7 + 130 x^{2} + 70))$

Step 4.1.1.2

Multiply $26$ by $7$ .

$f^{4} (x) = \frac{d}{d x} (14 x {(x^{2} + 7)}^{4} (26 x^{2} + 182 + 130 x^{2} + 70))$

Step 4.1.2

Simplify by adding terms.

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Step 4.1.2.1

Add $26 x^{2}$ and $130 x^{2}$ .

$f^{4} (x) = \frac{d}{d x} (14 x {(x^{2} + 7)}^{4} (156 x^{2} + 182 + 70))$

Step 4.1.2.2

Add $182$ and $70$ .

$f^{4} (x) = \frac{d}{d x} (14 x {(x^{2} + 7)}^{4} (156 x^{2} + 252))$

Step 4.1.3

Since $14$ is constant with respect to $x$ , the derivative of $14 x {(x^{2} + 7)}^{4} (156 x^{2} + 252)$ with respect to $x$ is $14 \frac{d}{d x} [x {(x^{2} + 7)}^{4} (156 x^{2} + 252)]$ .

$f^{4} (x) = 14 \frac{d}{d x} (x {(x^{2} + 7)}^{4} (156 x^{2} + 252))$

Step 4.2

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 $f (x) = x {(x^{2} + 7)}^{4}$ and $g (x) = 156 x^{2} + 252$ .

$f^{4} (x) = 14 (x {(x^{2} + 7)}^{4} \frac{d}{d x} (156 x^{2} + 252) + (156 x^{2} + 252) \frac{d}{d x} (x {(x^{2} + 7)}^{4}))$

Step 4.3

Differentiate.

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Step 4.3.1

By the Sum Rule, the derivative of $156 x^{2} + 252$ with respect to $x$ is $\frac{d}{d x} [156 x^{2}] + \frac{d}{d x} [252]$ .

$f^{4} (x) = 14 (x {(x^{2} + 7)}^{4} (\frac{d}{d x} (156 x^{2}) + \frac{d}{d x} (252)) + (156 x^{2} + 252) \frac{d}{d x} (x {(x^{2} + 7)}^{4}))$

Step 4.3.2

Since $156$ is constant with respect to $x$ , the derivative of $156 x^{2}$ with respect to $x$ is $156 \frac{d}{d x} [x^{2}]$ .

$f^{4} (x) = 14 (x {(x^{2} + 7)}^{4} (156 \frac{d}{d x} (x^{2}) + \frac{d}{d x} (252)) + (156 x^{2} + 252) \frac{d}{d x} (x {(x^{2} + 7)}^{4}))$

Step 4.3.3

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

$f^{4} (x) = 14 (x {(x^{2} + 7)}^{4} (156 (2 x) + \frac{d}{d x} (252)) + (156 x^{2} + 252) \frac{d}{d x} (x {(x^{2} + 7)}^{4}))$

Step 4.3.4

Multiply $2$ by $156$ .

$f^{4} (x) = 14 (x {(x^{2} + 7)}^{4} (312 x + \frac{d}{d x} (252)) + (156 x^{2} + 252) \frac{d}{d x} (x {(x^{2} + 7)}^{4}))$

Step 4.3.5

Since $252$ is constant with respect to $x$ , the derivative of $252$ with respect to $x$ is $0$ .

$f^{4} (x) = 14 (x {(x^{2} + 7)}^{4} (312 x + 0) + (156 x^{2} + 252) \frac{d}{d x} (x {(x^{2} + 7)}^{4}))$

Step 4.3.6

Add $312 x$ and $0$ .

$f^{4} (x) = 14 (x {(x^{2} + 7)}^{4} (312 x) + (156 x^{2} + 252) \frac{d}{d x} (x {(x^{2} + 7)}^{4}))$

Step 4.4

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

$f^{4} (x) = 14 (x \cdot x {(x^{2} + 7)}^{4} \cdot 312 + (156 x^{2} + 252) \frac{d}{d x} (x {(x^{2} + 7)}^{4}))$

Step 4.5

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

$f^{4} (x) = 14 (x \cdot x {(x^{2} + 7)}^{4} \cdot 312 + (156 x^{2} + 252) \frac{d}{d x} (x {(x^{2} + 7)}^{4}))$

Step 4.6

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

$f^{4} (x) = 14 (x^{1 + 1} {(x^{2} + 7)}^{4} \cdot 312 + (156 x^{2} + 252) \frac{d}{d x} (x {(x^{2} + 7)}^{4}))$

Step 4.7

Simplify the expression.

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Step 4.7.1

Add $1$ and $1$ .

$f^{4} (x) = 14 (x^{2} {(x^{2} + 7)}^{4} \cdot 312 + (156 x^{2} + 252) \frac{d}{d x} (x {(x^{2} + 7)}^{4}))$

Step 4.7.2

Move $312$ to the left of $x^{2} {(x^{2} + 7)}^{4}$ .

$f^{4} (x) = 14 (312 \cdot (x^{2} {(x^{2} + 7)}^{4}) + (156 x^{2} + 252) \frac{d}{d x} (x {(x^{2} + 7)}^{4}))$

Step 4.8

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 $f (x) = x$ and $g (x) = {(x^{2} + 7)}^{4}$ .

$f^{4} (x) = 14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x \frac{d}{d x} ({(x^{2} + 7)}^{4}) + {(x^{2} + 7)}^{4} \frac{d}{d x} (x)))$

Step 4.9

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = x^{4}$ and $g (x) = x^{2} + 7$ .

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Step 4.9.1

To apply the Chain Rule, set $u$ as $x^{2} + 7$ .

$f^{4} (x) = 14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x (\frac{d}{d u} (u^{4}) \frac{d}{d x} (x^{2} + 7)) + {(x^{2} + 7)}^{4} \frac{d}{d x} (x)))$

Step 4.9.2

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

$f^{4} (x) = 14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x (4 u^{3} \frac{d}{d x} (x^{2} + 7)) + {(x^{2} + 7)}^{4} \frac{d}{d x} (x)))$

Step 4.9.3

Replace all occurrences of $u$ with $x^{2} + 7$ .

$f^{4} (x) = 14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x (4 {(x^{2} + 7)}^{3} \frac{d}{d x} (x^{2} + 7)) + {(x^{2} + 7)}^{4} \frac{d}{d x} (x)))$

Step 4.10

Differentiate.

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Step 4.10.1

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

$f^{4} (x) = 14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x (4 {(x^{2} + 7)}^{3} (\frac{d}{d x} (x^{2}) + \frac{d}{d x} (7))) + {(x^{2} + 7)}^{4} \frac{d}{d x} (x)))$

Step 4.10.2

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

$f^{4} (x) = 14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x (4 {(x^{2} + 7)}^{3} (2 x + \frac{d}{d x} (7))) + {(x^{2} + 7)}^{4} \frac{d}{d x} (x)))$

Step 4.10.3

Since $7$ is constant with respect to $x$ , the derivative of $7$ with respect to $x$ is $0$ .

$f^{4} (x) = 14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x (4 {(x^{2} + 7)}^{3} (2 x + 0)) + {(x^{2} + 7)}^{4} \frac{d}{d x} (x)))$

Step 4.10.4

Simplify the expression.

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Step 4.10.4.1

Add $2 x$ and $0$ .

$f^{4} (x) = 14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x (4 {(x^{2} + 7)}^{3} (2 x)) + {(x^{2} + 7)}^{4} \frac{d}{d x} (x)))$

Step 4.10.4.2

Multiply $2$ by $4$ .

$f^{4} (x) = 14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x (8 {(x^{2} + 7)}^{3} x) + {(x^{2} + 7)}^{4} \frac{d}{d x} (x)))$

Step 4.11

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

$f^{4} (x) = 14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x \cdot x (8 {(x^{2} + 7)}^{3}) + {(x^{2} + 7)}^{4} \frac{d}{d x} (x)))$

Step 4.12

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

$f^{4} (x) = 14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x \cdot x (8 {(x^{2} + 7)}^{3}) + {(x^{2} + 7)}^{4} \frac{d}{d x} (x)))$

Step 4.13

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

$f^{4} (x) = 14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x^{1 + 1} (8 {(x^{2} + 7)}^{3}) + {(x^{2} + 7)}^{4} \frac{d}{d x} (x)))$

Step 4.14

Add $1$ and $1$ .

$f^{4} (x) = 14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x^{2} (8 {(x^{2} + 7)}^{3}) + {(x^{2} + 7)}^{4} \frac{d}{d x} (x)))$

Step 4.15

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

$f^{4} (x) = 14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x^{2} (8 {(x^{2} + 7)}^{3}) + {(x^{2} + 7)}^{4} \cdot 1))$

Step 4.16

Multiply ${(x^{2} + 7)}^{4}$ by $1$ .

$f^{4} (x) = 14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x^{2} (8 {(x^{2} + 7)}^{3}) + {(x^{2} + 7)}^{4}))$

Step 5

The fourth derivative of $f (x)$ with respect to $x$ is $14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x^{2} (8 {(x^{2} + 7)}^{3}) + {(x^{2} + 7)}^{4}))$ .

$14 (312 x^{2} {(x^{2} + 7)}^{4} + (156 x^{2} + 252) (x^{2} (8 {(x^{2} + 7)}^{3}) + {(x^{2} + 7)}^{4}))$