Calculus Examples

$f (x) = \frac{24}{x^{2} + 12}$

Step 1

Find the first derivative.

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Step 1.1

Differentiate using the Constant Multiple Rule.

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Step 1.1.1

Since $24$ is constant with respect to $x$ , the derivative of $\frac{24}{x^{2} + 12}$ with respect to $x$ is $24 \frac{d}{d x} [\frac{1}{x^{2} + 12}]$ .

$f' (x) = 24 \frac{d}{d x} (\frac{1}{x^{2} + 12})$

Step 1.1.2

Rewrite $\frac{1}{x^{2} + 12}$ as ${(x^{2} + 12)}^{- 1}$ .

$f' (x) = 24 \frac{d}{d x} ({(x^{2} + 12)}^{- 1})$

Step 1.2

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 $g (x) = x^{2} + 12$ .

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Step 1.2.1

To apply the Chain Rule, set $u$ as $x^{2} + 12$ .

$f' (x) = 24 (\frac{d}{d u} (u^{- 1}) \frac{d}{d x} (x^{2} + 12))$

Step 1.2.2

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

$f' (x) = 24 (- u^{- 2} \frac{d}{d x} (x^{2} + 12))$

Step 1.2.3

Replace all occurrences of $u$ with $x^{2} + 12$ .

$f' (x) = 24 (- {(x^{2} + 12)}^{- 2} \frac{d}{d x} (x^{2} + 12))$

Step 1.3

Differentiate.

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Step 1.3.1

Multiply $- 1$ by $24$ .

$f' (x) = - 24 ({(x^{2} + 12)}^{- 2} \frac{d}{d x} (x^{2} + 12))$

Step 1.3.2

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

$f' (x) = - 24 {(x^{2} + 12)}^{- 2} (\frac{d}{d x} (x^{2}) + \frac{d}{d x} (12))$

Step 1.3.3

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

$f' (x) = - 24 {(x^{2} + 12)}^{- 2} (2 x + \frac{d}{d x} (12))$

Step 1.3.4

Since $12$ is constant with respect to $x$ , the derivative of $12$ with respect to $x$ is $0$ .

$f' (x) = - 24 {(x^{2} + 12)}^{- 2} (2 x + 0)$

Step 1.3.5

Simplify the expression.

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Step 1.3.5.1

Add $2 x$ and $0$ .

$f' (x) = - 24 {(x^{2} + 12)}^{- 2} (2 x)$

Step 1.3.5.2

Multiply $2$ by $- 24$ .

$f' (x) = - 48 {(x^{2} + 12)}^{- 2} x$

Step 1.4

Simplify.

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Step 1.4.1

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

$f' (x) = - 48 \frac{1}{{(x^{2} + 12)}^{2}} \cdot x$

Step 1.4.2

Combine terms.

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Step 1.4.2.1

Combine $- 48$ and $\frac{1}{{(x^{2} + 12)}^{2}}$ .

$f' (x) = \frac{- 48}{{(x^{2} + 12)}^{2}} \cdot x$

Step 1.4.2.2

Move the negative in front of the fraction.

$f' (x) = - \frac{48}{{(x^{2} + 12)}^{2}} \cdot x$

Step 1.4.2.3

Combine $x$ and $\frac{48}{{(x^{2} + 12)}^{2}}$ .

$f' (x) = - \frac{x \cdot 48}{{(x^{2} + 12)}^{2}}$

Step 1.4.2.4

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

$f' (x) = - \frac{48 x}{{(x^{2} + 12)}^{2}}$

Step 2

Find the second derivative.

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Step 2.1

Since $- 48$ is constant with respect to $x$ , the derivative of $- \frac{48 x}{{(x^{2} + 12)}^{2}}$ with respect to $x$ is $- 48 \frac{d}{d x} [\frac{x}{{(x^{2} + 12)}^{2}}]$ .

$f'' (x) = - 48 \frac{d}{d x} \frac{x}{{(x^{2} + 12)}^{2}}$

Step 2.2

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

$f'' (x) = - 48 \frac{{(x^{2} + 12)}^{2} \frac{d}{d x} (x) - x \frac{d}{d x} {(x^{2} + 12)}^{2}}{{({(x^{2} + 12)}^{2})}^{2}}$

Step 2.3

Differentiate using the Power Rule.

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Step 2.3.1

Multiply the exponents in ${({(x^{2} + 12)}^{2})}^{2}$ .

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Step 2.3.1.1

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

$f'' (x) = - 48 \frac{{(x^{2} + 12)}^{2} \frac{d}{d x} (x) - x \frac{d}{d x} {(x^{2} + 12)}^{2}}{{(x^{2} + 12)}^{2 \cdot 2}}$

Step 2.3.1.2

Multiply $2$ by $2$ .

$f'' (x) = - 48 \frac{{(x^{2} + 12)}^{2} \frac{d}{d x} (x) - x \frac{d}{d x} {(x^{2} + 12)}^{2}}{{(x^{2} + 12)}^{4}}$

Step 2.3.2

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

$f'' (x) = - 48 \frac{{(x^{2} + 12)}^{2} \cdot 1 - x \frac{d}{d x} {(x^{2} + 12)}^{2}}{{(x^{2} + 12)}^{4}}$

Step 2.3.3

Multiply ${(x^{2} + 12)}^{2}$ by $1$ .

$f'' (x) = - 48 \frac{{(x^{2} + 12)}^{2} - x \frac{d}{d x} {(x^{2} + 12)}^{2}}{{(x^{2} + 12)}^{4}}$

Step 2.4

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = x^{2}$ and $g (x) = x^{2} + 12$ .

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Step 2.4.1

To apply the Chain Rule, set $u$ as $x^{2} + 12$ .

$f'' (x) = - 48 \frac{{(x^{2} + 12)}^{2} - x (\frac{d}{d u} (u^{2}) \frac{d}{d x} (x^{2} + 12))}{{(x^{2} + 12)}^{4}}$

Step 2.4.2

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

$f'' (x) = - 48 \frac{{(x^{2} + 12)}^{2} - x (2 u \frac{d}{d x} (x^{2} + 12))}{{(x^{2} + 12)}^{4}}$

Step 2.4.3

Replace all occurrences of $u$ with $x^{2} + 12$ .

$f'' (x) = - 48 \frac{{(x^{2} + 12)}^{2} - x (2 (x^{2} + 12) \frac{d}{d x} (x^{2} + 12))}{{(x^{2} + 12)}^{4}}$

Step 2.5

Simplify with factoring out.

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Step 2.5.1

Multiply $2$ by $- 1$ .

$f'' (x) = - 48 \frac{{(x^{2} + 12)}^{2} - 2 x ((x^{2} + 12) \frac{d}{d x} (x^{2} + 12))}{{(x^{2} + 12)}^{4}}$

Step 2.5.2

Factor $x^{2} + 12$ out of ${(x^{2} + 12)}^{2} - 2 x ((x^{2} + 12) \frac{d}{d x} [x^{2} + 12])$ .

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Step 2.5.2.1

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

$f'' (x) = - 48 \frac{(x^{2} + 12) (x^{2} + 12) - 2 x ((x^{2} + 12) \frac{d}{d x} (x^{2} + 12))}{{(x^{2} + 12)}^{4}}$

Step 2.5.2.2

Factor $x^{2} + 12$ out of $- 2 x ((x^{2} + 12) \frac{d}{d x} [x^{2} + 12])$ .

$f'' (x) = - 48 \frac{(x^{2} + 12) (x^{2} + 12) + (x^{2} + 12) (- 2 x (\frac{d}{d x} (x^{2} + 12)))}{{(x^{2} + 12)}^{4}}$

Step 2.5.2.3

Factor $x^{2} + 12$ out of $(x^{2} + 12) (x^{2} + 12) + (x^{2} + 12) (- 2 x (\frac{d}{d x} [x^{2} + 12]))$ .

$f'' (x) = - 48 \frac{(x^{2} + 12) (x^{2} + 12 - 2 x (\frac{d}{d x} (x^{2} + 12)))}{{(x^{2} + 12)}^{4}}$

Step 2.6

Cancel the common factors.

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Step 2.6.1

Factor $x^{2} + 12$ out of ${(x^{2} + 12)}^{4}$ .

$f'' (x) = - 48 \frac{(x^{2} + 12) (x^{2} + 12 - 2 x (\frac{d}{d x} (x^{2} + 12)))}{(x^{2} + 12) {(x^{2} + 12)}^{3}}$

Step 2.6.2

Cancel the common factor.

$f'' (x) = - 48 \frac{(x^{2} + 12) (x^{2} + 12 - 2 x (\frac{d}{d x} (x^{2} + 12)))}{(x^{2} + 12) {(x^{2} + 12)}^{3}}$

Step 2.6.3

Rewrite the expression.

$f'' (x) = - 48 \frac{x^{2} + 12 - 2 x (\frac{d}{d x} (x^{2} + 12))}{{(x^{2} + 12)}^{3}}$

Step 2.7

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

$f'' (x) = - 48 \frac{x^{2} + 12 - 2 x (\frac{d}{d x} (x^{2}) + \frac{d}{d x} (12))}{{(x^{2} + 12)}^{3}}$

Step 2.8

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

$f'' (x) = - 48 \frac{x^{2} + 12 - 2 x (2 x + \frac{d}{d x} (12))}{{(x^{2} + 12)}^{3}}$

Step 2.9

Since $12$ is constant with respect to $x$ , the derivative of $12$ with respect to $x$ is $0$ .

$f'' (x) = - 48 \frac{x^{2} + 12 - 2 x (2 x + 0)}{{(x^{2} + 12)}^{3}}$

Step 2.10

Simplify the expression.

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Step 2.10.1

Add $2 x$ and $0$ .

$f'' (x) = - 48 \frac{x^{2} + 12 - 2 x (2 x)}{{(x^{2} + 12)}^{3}}$

Step 2.10.2

Multiply $2$ by $- 2$ .

$f'' (x) = - 48 \frac{x^{2} + 12 - 4 x \cdot x}{{(x^{2} + 12)}^{3}}$

Step 2.11

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

$f'' (x) = - 48 \frac{x^{2} + 12 - 4 (x \cdot x)}{{(x^{2} + 12)}^{3}}$

Step 2.12

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

$f'' (x) = - 48 \frac{x^{2} + 12 - 4 (x \cdot x)}{{(x^{2} + 12)}^{3}}$

Step 2.13

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

$f'' (x) = - 48 \frac{x^{2} + 12 - 4 x^{1 + 1}}{{(x^{2} + 12)}^{3}}$

Step 2.14

Add $1$ and $1$ .

$f'' (x) = - 48 \frac{x^{2} + 12 - 4 x^{2}}{{(x^{2} + 12)}^{3}}$

Step 2.15

Subtract $4 x^{2}$ from $x^{2}$ .

$f'' (x) = - 48 \frac{- 3 x^{2} + 12}{{(x^{2} + 12)}^{3}}$

Step 2.16

Combine $- 48$ and $\frac{- 3 x^{2} + 12}{{(x^{2} + 12)}^{3}}$ .

$f'' (x) = \frac{- 48 (- 3 x^{2} + 12)}{{(x^{2} + 12)}^{3}}$

Step 2.17

Move the negative in front of the fraction.

$f'' (x) = - \frac{(48) (- 3 x^{2} + 12)}{{(x^{2} + 12)}^{3}}$

Step 2.18

Simplify.

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Step 2.18.1

Apply the distributive property.

$f'' (x) = - \frac{48 (- 3 x^{2}) + 48 \cdot 12}{{(x^{2} + 12)}^{3}}$

Step 2.18.2

Simplify each term.

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Step 2.18.2.1

Multiply $- 3$ by $48$ .

$f'' (x) = - \frac{- 144 x^{2} + 48 \cdot 12}{{(x^{2} + 12)}^{3}}$

Step 2.18.2.2

Multiply $48$ by $12$ .

$f'' (x) = - \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}}$

Step 3

Find the third derivative.

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Step 3.1

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 $f (x) = - 1$ and $g (x) = \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}}$ .

$f''' (x) = - \frac{d}{d x} \cdot \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.2

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} \frac{d}{d x} (- 144 x^{2} + 576) - (- 144 x^{2} + 576) \frac{d}{d x} {(x^{2} + 12)}^{3}}{{({(x^{2} + 12)}^{3})}^{2}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.3

Differentiate.

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Step 3.3.1

Multiply the exponents in ${({(x^{2} + 12)}^{3})}^{2}$ .

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Step 3.3.1.1

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

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} \frac{d}{d x} (- 144 x^{2} + 576) - (- 144 x^{2} + 576) \frac{d}{d x} {(x^{2} + 12)}^{3}}{{(x^{2} + 12)}^{3 \cdot 2}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.3.1.2

Multiply $3$ by $2$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} \frac{d}{d x} (- 144 x^{2} + 576) - (- 144 x^{2} + 576) \frac{d}{d x} {(x^{2} + 12)}^{3}}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.3.2

By the Sum Rule, the derivative of $- 144 x^{2} + 576$ with respect to $x$ is $\frac{d}{d x} [- 144 x^{2}] + \frac{d}{d x} [576]$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (\frac{d}{d x} (- 144 x^{2}) + \frac{d}{d x} (576)) - (- 144 x^{2} + 576) \frac{d}{d x} {(x^{2} + 12)}^{3}}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.3.3

Since $- 144$ is constant with respect to $x$ , the derivative of $- 144 x^{2}$ with respect to $x$ is $- 144 \frac{d}{d x} [x^{2}]$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 144 \frac{d}{d x} x^{2} + \frac{d}{d x} (576)) - (- 144 x^{2} + 576) \frac{d}{d x} {(x^{2} + 12)}^{3}}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.3.4

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

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 144 (2 x) + \frac{d}{d x} (576)) - (- 144 x^{2} + 576) \frac{d}{d x} {(x^{2} + 12)}^{3}}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.3.5

Multiply $2$ by $- 144$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x + \frac{d}{d x} (576)) - (- 144 x^{2} + 576) \frac{d}{d x} {(x^{2} + 12)}^{3}}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.3.6

Since $576$ is constant with respect to $x$ , the derivative of $576$ with respect to $x$ is $0$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x + 0) - (- 144 x^{2} + 576) \frac{d}{d x} {(x^{2} + 12)}^{3}}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.3.7

Add $- 288 x$ and $0$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x) - (- 144 x^{2} + 576) \frac{d}{d x} {(x^{2} + 12)}^{3}}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

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 $f (x) = x^{3}$ and $g (x) = x^{2} + 12$ .

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Step 3.4.1

To apply the Chain Rule, set $u$ as $x^{2} + 12$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x) - (- 144 x^{2} + 576) (\frac{d}{d u} (u^{3}) \frac{d}{d x} (x^{2} + 12))}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.4.2

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

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x) - (- 144 x^{2} + 576) (3 u^{2} \frac{d}{d x} (x^{2} + 12))}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.4.3

Replace all occurrences of $u$ with $x^{2} + 12$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x) - (- 144 x^{2} + 576) (3 {(x^{2} + 12)}^{2} \frac{d}{d x} (x^{2} + 12))}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.5

Differentiate.

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Step 3.5.1

Multiply $3$ by $- 1$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x) - 3 (- 144 x^{2} + 576) ({(x^{2} + 12)}^{2} \frac{d}{d x} (x^{2} + 12))}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.5.2

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

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x) - 3 (- 144 x^{2} + 576) ({(x^{2} + 12)}^{2} (\frac{d}{d x} (x^{2}) + \frac{d}{d x} (12)))}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.5.3

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

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x) - 3 (- 144 x^{2} + 576) ({(x^{2} + 12)}^{2} (2 x + \frac{d}{d x} (12)))}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.5.4

Since $12$ is constant with respect to $x$ , the derivative of $12$ with respect to $x$ is $0$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x) - 3 (- 144 x^{2} + 576) ({(x^{2} + 12)}^{2} (2 x + 0))}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.5.5

Simplify the expression.

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Step 3.5.5.1

Add $2 x$ and $0$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x) - 3 (- 144 x^{2} + 576) ({(x^{2} + 12)}^{2} (2 x))}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.5.5.2

Move $2$ to the left of ${(x^{2} + 12)}^{2}$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x) - 3 (- 144 x^{2} + 576) (2 \cdot ({(x^{2} + 12)}^{2} x))}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.5.5.3

Multiply $2$ by $- 3$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x) - 6 (- 144 x^{2} + 576) ({(x^{2} + 12)}^{2} x)}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot \frac{d}{d x} (- 1)$

Step 3.5.6

Since $- 1$ is constant with respect to $x$ , the derivative of $- 1$ with respect to $x$ is $0$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x) - 6 (- 144 x^{2} + 576) ({(x^{2} + 12)}^{2} x)}{{(x^{2} + 12)}^{6}} + \frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}} \cdot 0$

Step 3.5.7

Simplify the expression.

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Step 3.5.7.1

Multiply $\frac{- 144 x^{2} + 576}{{(x^{2} + 12)}^{3}}$ by $0$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x) - 6 (- 144 x^{2} + 576) ({(x^{2} + 12)}^{2} x)}{{(x^{2} + 12)}^{6}} + 0$

Step 3.5.7.2

Add $- \frac{{(x^{2} + 12)}^{3} (- 288 x) - 6 (- 144 x^{2} + 576) ({(x^{2} + 12)}^{2} x)}{{(x^{2} + 12)}^{6}}$ and $0$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x) - 6 (- 144 x^{2} + 576) ({(x^{2} + 12)}^{2} x)}{{(x^{2} + 12)}^{6}}$

Step 3.6

Simplify.

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Step 3.6.1

Apply the distributive property.

$f''' (x) = - \frac{{(x^{2} + 12)}^{3} (- 288 x) + (- 6 (- 144 x^{2}) - 6 \cdot 576) ({(x^{2} + 12)}^{2} x)}{{(x^{2} + 12)}^{6}}$

Step 3.6.2

Simplify the numerator.

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Step 3.6.2.1

Factor ${(x^{2} + 12)}^{2} x$ out of ${(x^{2} + 12)}^{3} (- 288 x) + (- 6 (- 144 x^{2}) - 6 \cdot 576) {(x^{2} + 12)}^{2} x$ .

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Step 3.6.2.1.1

Factor ${(x^{2} + 12)}^{2} x$ out of ${(x^{2} + 12)}^{3} (- 288 x)$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} x ((x^{2} + 12) \cdot (- 288)) + (- 6 (- 144 x^{2}) - 6 \cdot 576) {(x^{2} + 12)}^{2} x}{{(x^{2} + 12)}^{6}}$

Step 3.6.2.1.2

Factor ${(x^{2} + 12)}^{2} x$ out of $(- 6 (- 144 x^{2}) - 6 \cdot 576) {(x^{2} + 12)}^{2} x$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} x ((x^{2} + 12) \cdot (- 288)) + {(x^{2} + 12)}^{2} x (- 6 (- 144 x^{2}) - 6 \cdot 576)}{{(x^{2} + 12)}^{6}}$

Step 3.6.2.1.3

Factor ${(x^{2} + 12)}^{2} x$ out of ${(x^{2} + 12)}^{2} x ((x^{2} + 12) \cdot (- 288)) + {(x^{2} + 12)}^{2} x (- 6 (- 144 x^{2}) - 6 \cdot 576)$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} x ((x^{2} + 12) \cdot (- 288) - 6 (- 144 x^{2}) - 6 \cdot 576)}{{(x^{2} + 12)}^{6}}$

Step 3.6.2.2

Combine exponents.

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Step 3.6.2.2.1

Multiply $- 144$ by $- 6$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} x ((x^{2} + 12) \cdot (- 288) + 864 x^{2} - 6 \cdot 576)}{{(x^{2} + 12)}^{6}}$

Step 3.6.2.2.2

Multiply $- 6$ by $576$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} x ((x^{2} + 12) \cdot (- 288) + 864 x^{2} - 3456)}{{(x^{2} + 12)}^{6}}$

Step 3.6.2.3

Simplify each term.

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Step 3.6.2.3.1

Apply the distributive property.

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} x (x^{2} \cdot - 288 + 12 \cdot - 288 + 864 x^{2} - 3456)}{{(x^{2} + 12)}^{6}}$

Step 3.6.2.3.2

Move $- 288$ to the left of $x^{2}$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} x (- 288 \cdot x^{2} + 12 \cdot - 288 + 864 x^{2} - 3456)}{{(x^{2} + 12)}^{6}}$

Step 3.6.2.3.3

Multiply $12$ by $- 288$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} x (- 288 x^{2} - 3456 + 864 x^{2} - 3456)}{{(x^{2} + 12)}^{6}}$

Step 3.6.2.4

Add $- 288 x^{2}$ and $864 x^{2}$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} x (576 x^{2} - 3456 - 3456)}{{(x^{2} + 12)}^{6}}$

Step 3.6.2.5

Subtract $3456$ from $- 3456$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} x (576 x^{2} - 6912)}{{(x^{2} + 12)}^{6}}$

Step 3.6.2.6

Factor $576$ out of $576 x^{2} - 6912$ .

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Step 3.6.2.6.1

Factor $576$ out of $576 x^{2}$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} x (576 (x^{2}) - 6912)}{{(x^{2} + 12)}^{6}}$

Step 3.6.2.6.2

Factor $576$ out of $- 6912$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} x (576 x^{2} + 576 \cdot - 12)}{{(x^{2} + 12)}^{6}}$

Step 3.6.2.6.3

Factor $576$ out of $576 x^{2} + 576 \cdot - 12$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} x (576 (x^{2} - 12))}{{(x^{2} + 12)}^{6}}$

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} x \cdot (576 (x^{2} - 12))}{{(x^{2} + 12)}^{6}}$

Step 3.6.3

Combine terms.

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Step 3.6.3.1

Move $576$ to the left of ${(x^{2} + 12)}^{2} x$ .

$f''' (x) = - \frac{576 \cdot (({(x^{2} + 12)}^{2} x) (x^{2} - 12))}{{(x^{2} + 12)}^{6}}$

Step 3.6.3.2

Cancel the common factor of ${(x^{2} + 12)}^{2}$ and ${(x^{2} + 12)}^{6}$ .

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Step 3.6.3.2.1

Factor ${(x^{2} + 12)}^{2}$ out of $576 {(x^{2} + 12)}^{2} x (x^{2} - 12)$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} (576 x (x^{2} - 12))}{{(x^{2} + 12)}^{6}}$

Step 3.6.3.2.2

Cancel the common factors.

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Step 3.6.3.2.2.1

Factor ${(x^{2} + 12)}^{2}$ out of ${(x^{2} + 12)}^{6}$ .

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} (576 x (x^{2} - 12))}{{(x^{2} + 12)}^{2} {(x^{2} + 12)}^{4}}$

Step 3.6.3.2.2.2

Cancel the common factor.

$f''' (x) = - \frac{{(x^{2} + 12)}^{2} (576 x (x^{2} - 12))}{{(x^{2} + 12)}^{2} {(x^{2} + 12)}^{4}}$

Step 3.6.3.2.2.3

Rewrite the expression.

$f''' (x) = - \frac{576 x (x^{2} - 12)}{{(x^{2} + 12)}^{4}}$

Step 4

Find the fourth derivative.

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Step 4.1

Since $- 576$ is constant with respect to $x$ , the derivative of $- \frac{576 x (x^{2} - 12)}{{(x^{2} + 12)}^{4}}$ with respect to $x$ is $- 576 \frac{d}{d x} [\frac{x (x^{2} - 12)}{{(x^{2} + 12)}^{4}}]$ .

$f^{4} (x) = - 576 \frac{d}{d x} \frac{x (x^{2} - 12)}{{(x^{2} + 12)}^{4}}$

Step 4.2

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} \frac{d}{d x} (x (x^{2} - 12)) - x (x^{2} - 12) \frac{d}{d x} {(x^{2} + 12)}^{4}}{{({(x^{2} + 12)}^{4})}^{2}}$

Step 4.3

Multiply the exponents in ${({(x^{2} + 12)}^{4})}^{2}$ .

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Step 4.3.1

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

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} \frac{d}{d x} (x (x^{2} - 12)) - x (x^{2} - 12) \frac{d}{d x} {(x^{2} + 12)}^{4}}{{(x^{2} + 12)}^{4 \cdot 2}}$

Step 4.3.2

Multiply $4$ by $2$ .

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} \frac{d}{d x} (x (x^{2} - 12)) - x (x^{2} - 12) \frac{d}{d x} {(x^{2} + 12)}^{4}}{{(x^{2} + 12)}^{8}}$

Step 4.4

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 $f (x) = x$ and $g (x) = x^{2} - 12$ .

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} (x \frac{d}{d x} (x^{2} - 12) + (x^{2} - 12) \frac{d}{d x} (x)) - x (x^{2} - 12) \frac{d}{d x} {(x^{2} + 12)}^{4}}{{(x^{2} + 12)}^{8}}$

Step 4.5

Differentiate.

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Step 4.5.1

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

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} (x (\frac{d}{d x} (x^{2}) + \frac{d}{d x} (- 12)) + (x^{2} - 12) \frac{d}{d x} (x)) - x (x^{2} - 12) \frac{d}{d x} {(x^{2} + 12)}^{4}}{{(x^{2} + 12)}^{8}}$

Step 4.5.2

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

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} (x (2 x + \frac{d}{d x} (- 12)) + (x^{2} - 12) \frac{d}{d x} (x)) - x (x^{2} - 12) \frac{d}{d x} {(x^{2} + 12)}^{4}}{{(x^{2} + 12)}^{8}}$

Step 4.5.3

Since $- 12$ is constant with respect to $x$ , the derivative of $- 12$ with respect to $x$ is $0$ .

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} (x (2 x + 0) + (x^{2} - 12) \frac{d}{d x} (x)) - x (x^{2} - 12) \frac{d}{d x} {(x^{2} + 12)}^{4}}{{(x^{2} + 12)}^{8}}$

Step 4.5.4

Add $2 x$ and $0$ .

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} (x (2 x) + (x^{2} - 12) \frac{d}{d x} (x)) - x (x^{2} - 12) \frac{d}{d x} {(x^{2} + 12)}^{4}}{{(x^{2} + 12)}^{8}}$

Step 4.6

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

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} (2 (x \cdot x) + (x^{2} - 12) \frac{d}{d x} (x)) - x (x^{2} - 12) \frac{d}{d x} {(x^{2} + 12)}^{4}}{{(x^{2} + 12)}^{8}}$

Step 4.7

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

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} (2 (x \cdot x) + (x^{2} - 12) \frac{d}{d x} (x)) - x (x^{2} - 12) \frac{d}{d x} {(x^{2} + 12)}^{4}}{{(x^{2} + 12)}^{8}}$

Step 4.8

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

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} (2 x^{1 + 1} + (x^{2} - 12) \frac{d}{d x} (x)) - x (x^{2} - 12) \frac{d}{d x} {(x^{2} + 12)}^{4}}{{(x^{2} + 12)}^{8}}$

Step 4.9

Differentiate using the Power Rule.

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Step 4.9.1

Add $1$ and $1$ .

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} (2 x^{2} + (x^{2} - 12) \frac{d}{d x} (x)) - x (x^{2} - 12) \frac{d}{d x} {(x^{2} + 12)}^{4}}{{(x^{2} + 12)}^{8}}$

Step 4.9.2

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

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} (2 x^{2} + (x^{2} - 12) \cdot 1) - x (x^{2} - 12) \frac{d}{d x} {(x^{2} + 12)}^{4}}{{(x^{2} + 12)}^{8}}$

Step 4.9.3

Simplify by adding terms.

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Step 4.9.3.1

Multiply $x^{2} - 12$ by $1$ .

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} (2 x^{2} + x^{2} - 12) - x (x^{2} - 12) \frac{d}{d x} {(x^{2} + 12)}^{4}}{{(x^{2} + 12)}^{8}}$

Step 4.9.3.2

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

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} (3 x^{2} - 12) - x (x^{2} - 12) \frac{d}{d x} {(x^{2} + 12)}^{4}}{{(x^{2} + 12)}^{8}}$

Step 4.10

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 $g (x) = x^{2} + 12$ .

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Step 4.10.1

To apply the Chain Rule, set $u$ as $x^{2} + 12$ .

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} (3 x^{2} - 12) - x (x^{2} - 12) (\frac{d}{d u} (u^{4}) \frac{d}{d x} (x^{2} + 12))}{{(x^{2} + 12)}^{8}}$

Step 4.10.2

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

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} (3 x^{2} - 12) - x (x^{2} - 12) (4 u^{3} \frac{d}{d x} (x^{2} + 12))}{{(x^{2} + 12)}^{8}}$

Step 4.10.3

Replace all occurrences of $u$ with $x^{2} + 12$ .

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} (3 x^{2} - 12) - x (x^{2} - 12) (4 {(x^{2} + 12)}^{3} \frac{d}{d x} (x^{2} + 12))}{{(x^{2} + 12)}^{8}}$

Step 4.11

Simplify with factoring out.

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Step 4.11.1

Multiply $4$ by $- 1$ .

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{4} (3 x^{2} - 12) - 4 x (x^{2} - 12) ({(x^{2} + 12)}^{3} \frac{d}{d x} (x^{2} + 12))}{{(x^{2} + 12)}^{8}}$

Step 4.11.2

Factor ${(x^{2} + 12)}^{3}$ out of ${(x^{2} + 12)}^{4} (3 x^{2} - 12) - 4 x (x^{2} - 12) ({(x^{2} + 12)}^{3} \frac{d}{d x} [x^{2} + 12])$ .

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Step 4.11.2.1

Factor ${(x^{2} + 12)}^{3}$ out of ${(x^{2} + 12)}^{4} (3 x^{2} - 12)$ .

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{3} ((x^{2} + 12) (3 x^{2} - 12)) - 4 x (x^{2} - 12) ({(x^{2} + 12)}^{3} \frac{d}{d x} (x^{2} + 12))}{{(x^{2} + 12)}^{8}}$

Step 4.11.2.2

Factor ${(x^{2} + 12)}^{3}$ out of $- 4 x (x^{2} - 12) ({(x^{2} + 12)}^{3} \frac{d}{d x} [x^{2} + 12])$ .

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{3} ((x^{2} + 12) (3 x^{2} - 12)) + {(x^{2} + 12)}^{3} (- 4 x (x^{2} - 12) (\frac{d}{d x} (x^{2} + 12)))}{{(x^{2} + 12)}^{8}}$

Step 4.11.2.3

Factor ${(x^{2} + 12)}^{3}$ out of ${(x^{2} + 12)}^{3} ((x^{2} + 12) (3 x^{2} - 12)) + {(x^{2} + 12)}^{3} (- 4 x (x^{2} - 12) (\frac{d}{d x} [x^{2} + 12]))$ .

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{3} ((x^{2} + 12) (3 x^{2} - 12) - 4 x (x^{2} - 12) (\frac{d}{d x} (x^{2} + 12)))}{{(x^{2} + 12)}^{8}}$

Step 4.12

Cancel the common factors.

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Step 4.12.1

Factor ${(x^{2} + 12)}^{3}$ out of ${(x^{2} + 12)}^{8}$ .

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{3} ((x^{2} + 12) (3 x^{2} - 12) - 4 x (x^{2} - 12) (\frac{d}{d x} (x^{2} + 12)))}{{(x^{2} + 12)}^{3} {(x^{2} + 12)}^{5}}$

Step 4.12.2

Cancel the common factor.

$f^{4} (x) = - 576 \frac{{(x^{2} + 12)}^{3} ((x^{2} + 12) (3 x^{2} - 12) - 4 x (x^{2} - 12) (\frac{d}{d x} (x^{2} + 12)))}{{(x^{2} + 12)}^{3} {(x^{2} + 12)}^{5}}$

Step 4.12.3

Rewrite the expression.

$f^{4} (x) = - 576 \frac{(x^{2} + 12) (3 x^{2} - 12) - 4 x (x^{2} - 12) (\frac{d}{d x} (x^{2} + 12))}{{(x^{2} + 12)}^{5}}$

Step 4.13

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

$f^{4} (x) = - 576 \frac{(x^{2} + 12) (3 x^{2} - 12) - 4 x (x^{2} - 12) (\frac{d}{d x} (x^{2}) + \frac{d}{d x} (12))}{{(x^{2} + 12)}^{5}}$

Step 4.14

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

$f^{4} (x) = - 576 \frac{(x^{2} + 12) (3 x^{2} - 12) - 4 x (x^{2} - 12) (2 x + \frac{d}{d x} (12))}{{(x^{2} + 12)}^{5}}$

Step 4.15

Since $12$ is constant with respect to $x$ , the derivative of $12$ with respect to $x$ is $0$ .

$f^{4} (x) = - 576 \frac{(x^{2} + 12) (3 x^{2} - 12) - 4 x (x^{2} - 12) (2 x + 0)}{{(x^{2} + 12)}^{5}}$

Step 4.16

Simplify the expression.

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Step 4.16.1

Add $2 x$ and $0$ .

$f^{4} (x) = - 576 \frac{(x^{2} + 12) (3 x^{2} - 12) - 4 x (x^{2} - 12) (2 x)}{{(x^{2} + 12)}^{5}}$

Step 4.16.2

Multiply $2$ by $- 4$ .

$f^{4} (x) = - 576 \frac{(x^{2} + 12) (3 x^{2} - 12) - 8 x (x^{2} - 12) x}{{(x^{2} + 12)}^{5}}$

Step 4.17

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

$f^{4} (x) = - 576 \frac{(x^{2} + 12) (3 x^{2} - 12) - 8 (x \cdot x) (x^{2} - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.18

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

$f^{4} (x) = - 576 \frac{(x^{2} + 12) (3 x^{2} - 12) - 8 (x \cdot x) (x^{2} - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.19

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

$f^{4} (x) = - 576 \frac{(x^{2} + 12) (3 x^{2} - 12) - 8 x^{1 + 1} (x^{2} - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.20

Add $1$ and $1$ .

$f^{4} (x) = - 576 \frac{(x^{2} + 12) (3 x^{2} - 12) - 8 x^{2} (x^{2} - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.21

Combine $- 576$ and $\frac{(x^{2} + 12) (3 x^{2} - 12) - 8 x^{2} (x^{2} - 12)}{{(x^{2} + 12)}^{5}}$ .

$f^{4} (x) = \frac{- 576 ((x^{2} + 12) (3 x^{2} - 12) - 8 x^{2} (x^{2} - 12))}{{(x^{2} + 12)}^{5}}$

Step 4.22

Move the negative in front of the fraction.

$f^{4} (x) = - \frac{(576) ((x^{2} + 12) (3 x^{2} - 12) - 8 x^{2} (x^{2} - 12))}{{(x^{2} + 12)}^{5}}$

Step 4.23

Simplify.

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Step 4.23.1

Apply the distributive property.

$f^{4} (x) = - \frac{576 ((x^{2} + 12) (3 x^{2} - 12) - 8 x^{2} x^{2} - 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.2

Apply the distributive property.

$f^{4} (x) = - \frac{576 ((x^{2} + 12) (3 x^{2} - 12)) + 576 (- 8 x^{2} x^{2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3

Simplify the numerator.

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Step 4.23.3.1

Simplify each term.

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Step 4.23.3.1.1

Expand $(x^{2} + 12) (3 x^{2} - 12)$ using the FOIL Method.

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Step 4.23.3.1.1.1

Apply the distributive property.

$f^{4} (x) = - \frac{576 (x^{2} (3 x^{2} - 12) + 12 (3 x^{2} - 12)) + 576 (- 8 x^{2} x^{2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.1.2

Apply the distributive property.

$f^{4} (x) = - \frac{576 (x^{2} (3 x^{2}) + x^{2} \cdot - 12 + 12 (3 x^{2} - 12)) + 576 (- 8 x^{2} x^{2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.1.3

Apply the distributive property.

$f^{4} (x) = - \frac{576 (x^{2} (3 x^{2}) + x^{2} \cdot - 12 + 12 (3 x^{2}) + 12 \cdot - 12) + 576 (- 8 x^{2} x^{2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.2

Simplify and combine like terms.

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Step 4.23.3.1.2.1

Simplify each term.

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Step 4.23.3.1.2.1.1

Rewrite using the commutative property of multiplication.

$f^{4} (x) = - \frac{576 (3 x^{2} x^{2} + x^{2} \cdot - 12 + 12 (3 x^{2}) + 12 \cdot - 12) + 576 (- 8 x^{2} x^{2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.2.1.2

Multiply $x^{2}$ by $x^{2}$ by adding the exponents.

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Step 4.23.3.1.2.1.2.1

Move $x^{2}$ .

$f^{4} (x) = - \frac{576 (3 (x^{2} x^{2}) + x^{2} \cdot - 12 + 12 (3 x^{2}) + 12 \cdot - 12) + 576 (- 8 x^{2} x^{2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.2.1.2.2

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

$f^{4} (x) = - \frac{576 (3 x^{2 + 2} + x^{2} \cdot - 12 + 12 (3 x^{2}) + 12 \cdot - 12) + 576 (- 8 x^{2} x^{2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.2.1.2.3

Add $2$ and $2$ .

$f^{4} (x) = - \frac{576 (3 x^{4} + x^{2} \cdot - 12 + 12 (3 x^{2}) + 12 \cdot - 12) + 576 (- 8 x^{2} x^{2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.2.1.3

Move $- 12$ to the left of $x^{2}$ .

$f^{4} (x) = - \frac{576 (3 x^{4} - 12 \cdot x^{2} + 12 (3 x^{2}) + 12 \cdot - 12) + 576 (- 8 x^{2} x^{2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.2.1.4

Multiply $3$ by $12$ .

$f^{4} (x) = - \frac{576 (3 x^{4} - 12 x^{2} + 36 x^{2} + 12 \cdot - 12) + 576 (- 8 x^{2} x^{2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.2.1.5

Multiply $12$ by $- 12$ .

$f^{4} (x) = - \frac{576 (3 x^{4} - 12 x^{2} + 36 x^{2} - 144) + 576 (- 8 x^{2} x^{2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.2.2

Add $- 12 x^{2}$ and $36 x^{2}$ .

$f^{4} (x) = - \frac{576 (3 x^{4} + 24 x^{2} - 144) + 576 (- 8 x^{2} x^{2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.3

Apply the distributive property.

$f^{4} (x) = - \frac{576 (3 x^{4}) + 576 (24 x^{2}) + 576 \cdot - 144 + 576 (- 8 x^{2} x^{2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.4

Simplify.

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Step 4.23.3.1.4.1

Multiply $3$ by $576$ .

$f^{4} (x) = - \frac{1728 x^{4} + 576 (24 x^{2}) + 576 \cdot - 144 + 576 (- 8 x^{2} x^{2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.4.2

Multiply $24$ by $576$ .

$f^{4} (x) = - \frac{1728 x^{4} + 13824 x^{2} + 576 \cdot - 144 + 576 (- 8 x^{2} x^{2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.4.3

Multiply $576$ by $- 144$ .

$f^{4} (x) = - \frac{1728 x^{4} + 13824 x^{2} - 82944 + 576 (- 8 x^{2} x^{2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.5

Multiply $x^{2}$ by $x^{2}$ by adding the exponents.

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Step 4.23.3.1.5.1

Move $x^{2}$ .

$f^{4} (x) = - \frac{1728 x^{4} + 13824 x^{2} - 82944 + 576 (- 8 (x^{2} x^{2})) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.5.2

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

$f^{4} (x) = - \frac{1728 x^{4} + 13824 x^{2} - 82944 + 576 (- 8 x^{2 + 2}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.5.3

Add $2$ and $2$ .

$f^{4} (x) = - \frac{1728 x^{4} + 13824 x^{2} - 82944 + 576 (- 8 x^{4}) + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.6

Multiply $- 8$ by $576$ .

$f^{4} (x) = - \frac{1728 x^{4} + 13824 x^{2} - 82944 - 4608 x^{4} + 576 (- 8 x^{2} \cdot - 12)}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.7

Multiply $- 12$ by $- 8$ .

$f^{4} (x) = - \frac{1728 x^{4} + 13824 x^{2} - 82944 - 4608 x^{4} + 576 (96 x^{2})}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.1.8

Multiply $96$ by $576$ .

$f^{4} (x) = - \frac{1728 x^{4} + 13824 x^{2} - 82944 - 4608 x^{4} + 55296 x^{2}}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.2

Subtract $4608 x^{4}$ from $1728 x^{4}$ .

$f^{4} (x) = - \frac{- 2880 x^{4} + 13824 x^{2} - 82944 + 55296 x^{2}}{{(x^{2} + 12)}^{5}}$

Step 4.23.3.3

Add $13824 x^{2}$ and $55296 x^{2}$ .

$f^{4} (x) = - \frac{- 2880 x^{4} + 69120 x^{2} - 82944}{{(x^{2} + 12)}^{5}}$

Step 4.23.4

Factor $576$ out of $- 2880 x^{4} + 69120 x^{2} - 82944$ .

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Step 4.23.4.1

Factor $576$ out of $- 2880 x^{4}$ .

$f^{4} (x) = - \frac{576 (- 5 x^{4}) + 69120 x^{2} - 82944}{{(x^{2} + 12)}^{5}}$

Step 4.23.4.2

Factor $576$ out of $69120 x^{2}$ .

$f^{4} (x) = - \frac{576 (- 5 x^{4}) + 576 (120 x^{2}) - 82944}{{(x^{2} + 12)}^{5}}$

Step 4.23.4.3

Factor $576$ out of $- 82944$ .

$f^{4} (x) = - \frac{576 (- 5 x^{4}) + 576 (120 x^{2}) + 576 (- 144)}{{(x^{2} + 12)}^{5}}$

Step 4.23.4.4

Factor $576$ out of $576 (- 5 x^{4}) + 576 (120 x^{2})$ .

$f^{4} (x) = - \frac{576 (- 5 x^{4} + 120 x^{2}) + 576 (- 144)}{{(x^{2} + 12)}^{5}}$

Step 4.23.4.5

Factor $576$ out of $576 (- 5 x^{4} + 120 x^{2}) + 576 (- 144)$ .

$f^{4} (x) = - \frac{576 (- 5 x^{4} + 120 x^{2} - 144)}{{(x^{2} + 12)}^{5}}$

Step 4.23.5

Factor $- 1$ out of $- 5 x^{4}$ .

$f^{4} (x) = - \frac{576 (- (5 x^{4}) + 120 x^{2} - 144)}{{(x^{2} + 12)}^{5}}$

Step 4.23.6

Factor $- 1$ out of $120 x^{2}$ .

$f^{4} (x) = - \frac{576 (- (5 x^{4}) - (- 120 x^{2}) - 144)}{{(x^{2} + 12)}^{5}}$

Step 4.23.7

Factor $- 1$ out of $- (5 x^{4}) - (- 120 x^{2})$ .

$f^{4} (x) = - \frac{576 (- (5 x^{4} - 120 x^{2}) - 144)}{{(x^{2} + 12)}^{5}}$

Step 4.23.8

Rewrite $- 144$ as $- 1 (144)$ .

$f^{4} (x) = - \frac{576 (- (5 x^{4} - 120 x^{2}) - 1 \cdot 144)}{{(x^{2} + 12)}^{5}}$

Step 4.23.9

Factor $- 1$ out of $- (5 x^{4} - 120 x^{2}) - 1 (144)$ .

$f^{4} (x) = - \frac{576 (- (5 x^{4} - 120 x^{2} + 144))}{{(x^{2} + 12)}^{5}}$

Step 4.23.10

Rewrite $- (5 x^{4} - 120 x^{2} + 144)$ as $- 1 (5 x^{4} - 120 x^{2} + 144)$ .

$f^{4} (x) = - \frac{576 (- 1 (5 x^{4} - 120 x^{2} + 144))}{{(x^{2} + 12)}^{5}}$

Step 4.23.11

Move the negative in front of the fraction.

$f^{4} (x) = \frac{576 (5 x^{4} - 120 x^{2} + 144)}{{(x^{2} + 12)}^{5}}$

Step 4.23.12

Multiply $- 1$ by $- 1$ .

$f^{4} (x) = 1 (\frac{576 (5 x^{4} - 120 x^{2} + 144)}{{(x^{2} + 12)}^{5}})$

Step 4.23.13

Multiply $\frac{576 (5 x^{4} - 120 x^{2} + 144)}{{(x^{2} + 12)}^{5}}$ by $1$ .

$f^{4} (x) = \frac{576 (5 x^{4} - 120 x^{2} + 144)}{{(x^{2} + 12)}^{5}}$

Step 5

The fourth derivative of $f (x)$ with respect to $x$ is $\frac{576 (5 x^{4} - 120 x^{2} + 144)}{{(x^{2} + 12)}^{5}}$ .

$\frac{576 (5 x^{4} - 120 x^{2} + 144)}{{(x^{2} + 12)}^{5}}$