Calculus Examples

$\frac{\sin^{2} (3 x)}{\cos (3 x)}$

Step 1

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 $f (x) = \sin^{2} (3 x)$ and $g (x) = \cos (3 x)$ .

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

Step 2

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = x^{2}$ and $g (x) = \sin (3 x)$ .

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Step 2.1

To apply the Chain Rule, set $u_{1}$ as $\sin (3 x)$ .

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

Step 2.2

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

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

Step 2.3

Replace all occurrences of $u_{1}$ with $\sin (3 x)$ .

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

Step 3

Move $2$ to the left of $\cos (3 x)$ .

$\frac{2 \cdot \cos (3 x) \sin (3 x) \frac{d}{d x} [\sin (3 x)] - \sin^{2} (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}$

Step 4

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

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Step 4.1

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

$\frac{2 \cos (3 x) \sin (3 x) (\frac{d}{d u_{2}} [\sin (u_{2})] \frac{d}{d x} [3 x]) - \sin^{2} (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}$

Step 4.2

The derivative of $\sin (u_{2})$ with respect to $u_{2}$ is $\cos (u_{2})$ .

$\frac{2 \cos (3 x) \sin (3 x) (\cos (u_{2}) \frac{d}{d x} [3 x]) - \sin^{2} (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}$

Step 4.3

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

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

Step 5

Raise $\cos (3 x)$ to the power of $1$ .

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

Step 6

Raise $\cos (3 x)$ to the power of $1$ .

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

Step 7

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

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

Step 8

Differentiate.

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Step 8.1

Add $1$ and $1$ .

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

Step 8.2

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

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

Step 8.3

Multiply $3$ by $2$ .

$\frac{6 \cos^{2} (3 x) \sin (3 x) \frac{d}{d x} [x] - \sin^{2} (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}$

Step 8.4

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

$\frac{6 \cos^{2} (3 x) \sin (3 x) \cdot 1 - \sin^{2} (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}$

Step 8.5

Multiply $6$ by $1$ .

$\frac{6 \cos^{2} (3 x) \sin (3 x) - \sin^{2} (3 x) \frac{d}{d x} [\cos (3 x)]}{\cos^{2} (3 x)}$

Step 9

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

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Step 9.1

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

$\frac{6 \cos^{2} (3 x) \sin (3 x) - \sin^{2} (3 x) (\frac{d}{d u_{3}} [\cos (u_{3})] \frac{d}{d x} [3 x])}{\cos^{2} (3 x)}$

Step 9.2

The derivative of $\cos (u_{3})$ with respect to $u_{3}$ is $- \sin (u_{3})$ .

$\frac{6 \cos^{2} (3 x) \sin (3 x) - \sin^{2} (3 x) (- \sin (u_{3}) \frac{d}{d x} [3 x])}{\cos^{2} (3 x)}$

Step 9.3

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

$\frac{6 \cos^{2} (3 x) \sin (3 x) - \sin^{2} (3 x) (- \sin (3 x) \frac{d}{d x} [3 x])}{\cos^{2} (3 x)}$

Step 10

Multiply.

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Step 10.1

Multiply $- 1$ by $- 1$ .

$\frac{6 \cos^{2} (3 x) \sin (3 x) + 1 \sin^{2} (3 x) (\sin (3 x) \frac{d}{d x} [3 x])}{\cos^{2} (3 x)}$

Step 10.2

Multiply $\sin^{2} (3 x)$ by $1$ .

$\frac{6 \cos^{2} (3 x) \sin (3 x) + \sin^{2} (3 x) (\sin (3 x) \frac{d}{d x} [3 x])}{\cos^{2} (3 x)}$

Step 11

Multiply $\sin^{2} (3 x)$ by $\sin (3 x)$ by adding the exponents.

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Step 11.1

Move $\sin (3 x)$ .

$\frac{6 \cos^{2} (3 x) \sin (3 x) + \sin (3 x) \sin^{2} (3 x) \frac{d}{d x} [3 x]}{\cos^{2} (3 x)}$

Step 11.2

Multiply $\sin (3 x)$ by $\sin^{2} (3 x)$ .

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Step 11.2.1

Raise $\sin (3 x)$ to the power of $1$ .

$\frac{6 \cos^{2} (3 x) \sin (3 x) + \sin^{1} (3 x) \sin^{2} (3 x) \frac{d}{d x} [3 x]}{\cos^{2} (3 x)}$

Step 11.2.2

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

$\frac{6 \cos^{2} (3 x) \sin (3 x) + {\sin (3 x)}^{1 + 2} \frac{d}{d x} [3 x]}{\cos^{2} (3 x)}$

Step 11.3

Add $1$ and $2$ .

$\frac{6 \cos^{2} (3 x) \sin (3 x) + \sin^{3} (3 x) \frac{d}{d x} [3 x]}{\cos^{2} (3 x)}$

Step 12

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

$\frac{6 \cos^{2} (3 x) \sin (3 x) + \sin^{3} (3 x) (3 \frac{d}{d x} [x])}{\cos^{2} (3 x)}$

Step 13

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

$\frac{6 \cos^{2} (3 x) \sin (3 x) + \sin^{3} (3 x) (3 \cdot 1)}{\cos^{2} (3 x)}$

Step 14

Simplify the expression.

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Step 14.1

Multiply $3$ by $1$ .

$\frac{6 \cos^{2} (3 x) \sin (3 x) + \sin^{3} (3 x) \cdot 3}{\cos^{2} (3 x)}$

Step 14.2

Move $3$ to the left of $\sin^{3} (3 x)$ .

$\frac{6 \cos^{2} (3 x) \sin (3 x) + 3 \sin^{3} (3 x)}{\cos^{2} (3 x)}$