Calculus Examples

$f (x) = 4 \sin (x) + 3 x^{x}$

Step 1

By the Sum Rule, the derivative of $4 \sin (x) + 3 x^{x}$ with respect to $x$ is $\frac{d}{d x} [4 \sin (x)] + \frac{d}{d x} [3 x^{x}]$ .

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

Step 2

Evaluate $\frac{d}{d x} [4 \sin (x)]$ .

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Step 2.1

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

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

Step 2.2

The derivative of $\sin (x)$ with respect to $x$ is $\cos (x)$ .

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

Step 3

Evaluate $\frac{d}{d x} [3 x^{x}]$ .

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Step 3.1

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

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

Step 3.2

Use the properties of logarithms to simplify the differentiation.

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Step 3.2.1

Rewrite $x^{x}$ as $e^{\ln (x^{x})}$ .

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

Step 3.2.2

Expand $\ln (x^{x})$ by moving $x$ outside the logarithm.

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

Step 3.3

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

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Step 3.3.1

To apply the Chain Rule, set $u$ as $x \ln (x)$ .

$4 \cos (x) + 3 (\frac{d}{d u} [e^{u}] \frac{d}{d x} [x \ln (x)])$

Step 3.3.2

Differentiate using the Exponential Rule which states that $\frac{d}{d u} [a^{u}]$ is $a^{u} \ln (a)$ where $a$ = $e$ .

$4 \cos (x) + 3 (e^{u} \frac{d}{d x} [x \ln (x)])$

Step 3.3.3

Replace all occurrences of $u$ with $x \ln (x)$ .

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

Step 3.4

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 $g (x) = \ln (x)$ .

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

Step 3.5

The derivative of $\ln (x)$ with respect to $x$ is $\frac{1}{x}$ .

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

Step 3.6

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

$4 \cos (x) + 3 (e^{x \ln (x)} (x \frac{1}{x} + \ln (x) \cdot 1))$

Step 3.7

Combine $x$ and $\frac{1}{x}$ .

$4 \cos (x) + 3 (e^{x \ln (x)} (\frac{x}{x} + \ln (x) \cdot 1))$

Step 3.8

Cancel the common factor of $x$ .

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Step 3.8.1

Cancel the common factor.

$4 \cos (x) + 3 (e^{x \ln (x)} (\frac{x}{x} + \ln (x) \cdot 1))$

Step 3.8.2

Rewrite the expression.

$4 \cos (x) + 3 (e^{x \ln (x)} (1 + \ln (x) \cdot 1))$

Step 3.9

Multiply $\ln (x)$ by $1$ .

$4 \cos (x) + 3 e^{x \ln (x)} (1 + \ln (x))$

Step 4

Simplify.

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Step 4.1

Apply the distributive property.

$4 \cos (x) + 3 e^{x \ln (x)} \cdot 1 + 3 e^{x \ln (x)} \ln (x)$

Step 4.2

Multiply $3$ by $1$ .

$4 \cos (x) + 3 e^{x \ln (x)} + 3 e^{x \ln (x)} \ln (x)$

Step 4.3

Reorder terms.

$3 e^{x \ln (x)} \ln (x) + 3 e^{x \ln (x)} + 4 \cos (x)$