Calculus Examples

$y = {(x^{3} + 1)}^{5} \cos (4 x^{3})$

Step 1

Differentiate both sides of the equation.

$\frac{d}{d x} (y) = \frac{d}{d x} ({(x^{3} + 1)}^{5} \cos (4 x^{3}))$

Step 2

The derivative of $y$ with respect to $x$ is $y'$ .

$y'$

Step 3

Differentiate the right side of the equation.

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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 $f (x) = {(x^{3} + 1)}^{5}$ and $g (x) = \cos (4 x^{3})$ .

${(x^{3} + 1)}^{5} \frac{d}{d x} [\cos (4 x^{3})] + \cos (4 x^{3}) \frac{d}{d x} [{(x^{3} + 1)}^{5}]$

Step 3.2

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = \cos (x)$ and $g (x) = 4 x^{3}$ .

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Step 3.2.1

To apply the Chain Rule, set $u_{1}$ as $4 x^{3}$ .

${(x^{3} + 1)}^{5} (\frac{d}{d u_{1}} [\cos (u_{1})] \frac{d}{d x} [4 x^{3}]) + \cos (4 x^{3}) \frac{d}{d x} [{(x^{3} + 1)}^{5}]$

Step 3.2.2

The derivative of $\cos (u_{1})$ with respect to $u_{1}$ is $- \sin (u_{1})$ .

${(x^{3} + 1)}^{5} (- \sin (u_{1}) \frac{d}{d x} [4 x^{3}]) + \cos (4 x^{3}) \frac{d}{d x} [{(x^{3} + 1)}^{5}]$

Step 3.2.3

Replace all occurrences of $u_{1}$ with $4 x^{3}$ .

${(x^{3} + 1)}^{5} (- \sin (4 x^{3}) \frac{d}{d x} [4 x^{3}]) + \cos (4 x^{3}) \frac{d}{d x} [{(x^{3} + 1)}^{5}]$

Step 3.3

Differentiate.

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Step 3.3.1

Since $4$ is constant with respect to $x$ , the derivative of $4 x^{3}$ with respect to $x$ is $4 \frac{d}{d x} [x^{3}]$ .

${(x^{3} + 1)}^{5} (- \sin (4 x^{3}) (4 \frac{d}{d x} [x^{3}])) + \cos (4 x^{3}) \frac{d}{d x} [{(x^{3} + 1)}^{5}]$

Step 3.3.2

Multiply $4$ by $- 1$ .

${(x^{3} + 1)}^{5} (- 4 \sin (4 x^{3}) \frac{d}{d x} [x^{3}]) + \cos (4 x^{3}) \frac{d}{d x} [{(x^{3} + 1)}^{5}]$

Step 3.3.3

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

${(x^{3} + 1)}^{5} (- 4 \sin (4 x^{3}) (3 x^{2})) + \cos (4 x^{3}) \frac{d}{d x} [{(x^{3} + 1)}^{5}]$

Step 3.3.4

Multiply $3$ by $- 4$ .

${(x^{3} + 1)}^{5} (- 12 \sin (4 x^{3}) x^{2}) + \cos (4 x^{3}) \frac{d}{d x} [{(x^{3} + 1)}^{5}]$

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

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Step 3.4.1

To apply the Chain Rule, set $u_{2}$ as $x^{3} + 1$ .

${(x^{3} + 1)}^{5} (- 12 \sin (4 x^{3}) x^{2}) + \cos (4 x^{3}) (\frac{d}{d u_{2}} [{u_{2}}^{5}] \frac{d}{d x} [x^{3} + 1])$

Step 3.4.2

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

${(x^{3} + 1)}^{5} (- 12 \sin (4 x^{3}) x^{2}) + \cos (4 x^{3}) (5 {u_{2}}^{4} \frac{d}{d x} [x^{3} + 1])$

Step 3.4.3

Replace all occurrences of $u_{2}$ with $x^{3} + 1$ .

${(x^{3} + 1)}^{5} (- 12 \sin (4 x^{3}) x^{2}) + \cos (4 x^{3}) (5 {(x^{3} + 1)}^{4} \frac{d}{d x} [x^{3} + 1])$

Step 3.5

Differentiate.

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Step 3.5.1

By the Sum Rule, the derivative of $x^{3} + 1$ with respect to $x$ is $\frac{d}{d x} [x^{3}] + \frac{d}{d x} [1]$ .

${(x^{3} + 1)}^{5} (- 12 \sin (4 x^{3}) x^{2}) + \cos (4 x^{3}) (5 {(x^{3} + 1)}^{4} (\frac{d}{d x} [x^{3}] + \frac{d}{d x} [1]))$

Step 3.5.2

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

${(x^{3} + 1)}^{5} (- 12 \sin (4 x^{3}) x^{2}) + \cos (4 x^{3}) (5 {(x^{3} + 1)}^{4} (3 x^{2} + \frac{d}{d x} [1]))$

Step 3.5.3

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

${(x^{3} + 1)}^{5} (- 12 \sin (4 x^{3}) x^{2}) + \cos (4 x^{3}) (5 {(x^{3} + 1)}^{4} (3 x^{2} + 0))$

Step 3.5.4

Simplify the expression.

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Step 3.5.4.1

Add $3 x^{2}$ and $0$ .

${(x^{3} + 1)}^{5} (- 12 \sin (4 x^{3}) x^{2}) + \cos (4 x^{3}) (5 {(x^{3} + 1)}^{4} (3 x^{2}))$

Step 3.5.4.2

Multiply $3$ by $5$ .

${(x^{3} + 1)}^{5} (- 12 \sin (4 x^{3}) x^{2}) + \cos (4 x^{3}) (15 {(x^{3} + 1)}^{4} x^{2})$

Step 3.5.4.3

Reorder terms.

$- 12 x^{2} {(x^{3} + 1)}^{5} \sin (4 x^{3}) + 15 x^{2} {(x^{3} + 1)}^{4} \cos (4 x^{3})$

Step 4

Reform the equation by setting the left side equal to the right side.

$y' = - 12 x^{2} {(x^{3} + 1)}^{5} \sin (4 x^{3}) + 15 x^{2} {(x^{3} + 1)}^{4} \cos (4 x^{3})$

Step 5

Replace $y'$ with $\frac{d y}{d x}$ .

$\frac{d y}{d x} = - 12 x^{2} {(x^{3} + 1)}^{5} \sin (4 x^{3}) + 15 x^{2} {(x^{3} + 1)}^{4} \cos (4 x^{3})$