Calculus Examples

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

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

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

Step 2

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

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Step 2.1

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

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

Step 2.2

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

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

Step 2.3

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

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

Step 3

Differentiate.

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Step 3.1

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

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

Step 3.2

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

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

Step 3.3

Multiply $2$ by $3$ .

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

Step 4

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

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Step 4.1

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

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

Step 4.2

The derivative of $\log (u_{2})$ with respect to $u_{2}$ is $\frac{1}{u_{2} \ln (10)}$ .

$\frac{\log (\cos (3 x)) \cos (3 x^{2}) (6 x) - \sin (3 x^{2}) (\frac{1}{u_{2} \ln (10)} \frac{d}{d x} [\cos (3 x)])}{\log^{2} (\cos (3 x))}$

Step 4.3

Replace all occurrences of $u_{2}$ with $\cos (3 x)$ .

$\frac{\log (\cos (3 x)) \cos (3 x^{2}) (6 x) - \sin (3 x^{2}) (\frac{1}{\cos (3 x) \ln (10)} \frac{d}{d x} [\cos (3 x)])}{\log^{2} (\cos (3 x))}$

Step 5

Combine $\frac{1}{\cos (3 x) \ln (10)}$ and $\sin (3 x^{2})$ .

$\frac{\log (\cos (3 x)) \cos (3 x^{2}) (6 x) - \frac{\sin (3 x^{2})}{\cos (3 x) \ln (10)} \frac{d}{d x} [\cos (3 x)]}{\log^{2} (\cos (3 x))}$

Step 6

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 6.1

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

$\frac{\log (\cos (3 x)) \cos (3 x^{2}) (6 x) - \frac{\sin (3 x^{2})}{\cos (3 x) \ln (10)} (\frac{d}{d u_{3}} [\cos (u_{3})] \frac{d}{d x} [3 x])}{\log^{2} (\cos (3 x))}$

Step 6.2

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

$\frac{\log (\cos (3 x)) \cos (3 x^{2}) (6 x) - \frac{\sin (3 x^{2})}{\cos (3 x) \ln (10)} (- \sin (u_{3}) \frac{d}{d x} [3 x])}{\log^{2} (\cos (3 x))}$

Step 6.3

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

$\frac{\log (\cos (3 x)) \cos (3 x^{2}) (6 x) - \frac{\sin (3 x^{2})}{\cos (3 x) \ln (10)} (- \sin (3 x) \frac{d}{d x} [3 x])}{\log^{2} (\cos (3 x))}$

Step 7

Differentiate.

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Step 7.1

Multiply $- 1$ by $- 1$ .

$\frac{\log (\cos (3 x)) \cos (3 x^{2}) (6 x) + 1 \frac{\sin (3 x^{2})}{\cos (3 x) \ln (10)} (\sin (3 x) \frac{d}{d x} [3 x])}{\log^{2} (\cos (3 x))}$

Step 7.2

Combine fractions.

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Step 7.2.1

Multiply $\frac{\sin (3 x^{2})}{\cos (3 x) \ln (10)}$ by $1$ .

$\frac{\log (\cos (3 x)) \cos (3 x^{2}) (6 x) + \frac{\sin (3 x^{2})}{\cos (3 x) \ln (10)} (\sin (3 x) \frac{d}{d x} [3 x])}{\log^{2} (\cos (3 x))}$

Step 7.2.2

Combine $\sin (3 x)$ and $\frac{\sin (3 x^{2})}{\cos (3 x) \ln (10)}$ .

$\frac{\log (\cos (3 x)) \cos (3 x^{2}) (6 x) + \frac{\sin (3 x) \sin (3 x^{2})}{\cos (3 x) \ln (10)} \frac{d}{d x} [3 x]}{\log^{2} (\cos (3 x))}$

Step 7.3

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

$\frac{\log (\cos (3 x)) \cos (3 x^{2}) (6 x) + \frac{\sin (3 x) \sin (3 x^{2})}{\cos (3 x) \ln (10)} (3 \frac{d}{d x} [x])}{\log^{2} (\cos (3 x))}$

Step 7.4

Combine $3$ and $\frac{\sin (3 x) \sin (3 x^{2})}{\cos (3 x) \ln (10)}$ .

$\frac{\log (\cos (3 x)) \cos (3 x^{2}) (6 x) + \frac{3 (\sin (3 x) \sin (3 x^{2}))}{\cos (3 x) \ln (10)} \frac{d}{d x} [x]}{\log^{2} (\cos (3 x))}$

Step 7.5

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

$\frac{\log (\cos (3 x)) \cos (3 x^{2}) (6 x) + \frac{3 \sin (3 x) \sin (3 x^{2})}{\cos (3 x) \ln (10)} \cdot 1}{\log^{2} (\cos (3 x))}$

Step 7.6

Multiply $\frac{3 \sin (3 x) \sin (3 x^{2})}{\cos (3 x) \ln (10)}$ by $1$ .

$\frac{\log (\cos (3 x)) \cos (3 x^{2}) (6 x) + \frac{3 \sin (3 x) \sin (3 x^{2})}{\cos (3 x) \ln (10)}}{\log^{2} (\cos (3 x))}$

Step 8

Multiply $\frac{\log (\cos (3 x)) \cos (3 x^{2}) (6 x) + \frac{3 \sin (3 x) \sin (3 x^{2})}{\cos (3 x) \ln (10)}}{\log^{2} (\cos (3 x))}$ by $\frac{\cos (3 x) \ln (10)}{\cos (3 x) \ln (10)}$ .

$\frac{\cos (3 x) \ln (10)}{\cos (3 x) \ln (10)} \cdot \frac{\log (\cos (3 x)) \cos (3 x^{2}) (6 x) + \frac{3 \sin (3 x) \sin (3 x^{2})}{\cos (3 x) \ln (10)}}{\log^{2} (\cos (3 x))}$

Step 9

Combine.

$\frac{\cos (3 x) \ln (10) (\log (\cos (3 x)) \cos (3 x^{2}) (6 x) + \frac{3 \sin (3 x) \sin (3 x^{2})}{\cos (3 x) \ln (10)})}{\cos (3 x) \ln (10) \log^{2} (\cos (3 x))}$

Step 10

Apply the distributive property.

$\frac{\cos (3 x) \ln (10) (\log (\cos (3 x)) \cos (3 x^{2}) (6 x)) + \cos (3 x) \ln (10) \frac{3 \sin (3 x) \sin (3 x^{2})}{\cos (3 x) \ln (10)}}{\cos (3 x) \ln (10) \log^{2} (\cos (3 x))}$

Step 11

Cancel the common factor of $\cos (3 x) \ln (10)$ .

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Step 11.1

Cancel the common factor.

$\frac{\cos (3 x) \ln (10) (\log (\cos (3 x)) \cos (3 x^{2}) (6 x)) + \cos (3 x) \ln (10) \frac{3 \sin (3 x) \sin (3 x^{2})}{\cos (3 x) \ln (10)}}{\cos (3 x) \ln (10) \log^{2} (\cos (3 x))}$

Step 11.2

Rewrite the expression.

$\frac{\cos (3 x) \ln (10) (\log (\cos (3 x)) \cos (3 x^{2}) (6 x)) + 3 \sin (3 x) \sin (3 x^{2})}{\cos (3 x) \ln (10) \log^{2} (\cos (3 x))}$

Step 12

Simplify.

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Step 12.1

Simplify the numerator.

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Step 12.1.1

Simplify each term.

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Step 12.1.1.1

Simplify $6 \ln (10)$ by moving $6$ inside the logarithm.

$\frac{\cos (3 x) \ln (10^{6}) \log (\cos (3 x)) \cos (3 x^{2}) x + 3 \sin (3 x) \sin (3 x^{2})}{\cos (3 x) \ln (10) \log^{2} (\cos (3 x))}$

Step 12.1.1.2

Raise $10$ to the power of $6$ .

$\frac{\cos (3 x) \ln (1000000) \log (\cos (3 x)) \cos (3 x^{2}) x + 3 \sin (3 x) \sin (3 x^{2})}{\cos (3 x) \ln (10) \log^{2} (\cos (3 x))}$

Step 12.1.2

Reorder factors in $\cos (3 x) \ln (1000000) \log (\cos (3 x)) \cos (3 x^{2}) x + 3 \sin (3 x) \sin (3 x^{2})$ .

$\frac{x \cos (3 x) \ln (1000000) \log (\cos (3 x)) \cos (3 x^{2}) + 3 \sin (3 x) \sin (3 x^{2})}{\cos (3 x) \ln (10) \log^{2} (\cos (3 x))}$

Step 12.2

Reorder terms.

$\frac{x \cos (3 x) \cos (3 x^{2}) \ln (1000000) \log (\cos (3 x)) + 3 \sin (3 x) \sin (3 x^{2})}{\log^{2} (\cos (3 x)) \cos (3 x) \ln (10)}$