Precalculus Examples

$f (x) = \frac{1 + x}{e^{\cos (x)}}$

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

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

Step 2

Differentiate.

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Step 2.1

Multiply the exponents in ${(e^{\cos (x)})}^{2}$ .

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Step 2.1.1

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

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

Step 2.1.2

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

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

Step 2.2

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

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

Step 2.3

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

$\frac{e^{\cos (x)} (0 + \frac{d}{d x} [x]) - (1 + x) \frac{d}{d x} [e^{\cos (x)}]}{e^{2 \cos (x)}}$

Step 2.4

Add $0$ and $\frac{d}{d x} [x]$ .

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

Step 2.5

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

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

Step 2.6

Multiply $e^{\cos (x)}$ by $1$ .

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

Step 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 $g (x) = \cos (x)$ .

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Step 3.1

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

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

Step 3.2

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

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

Step 3.3

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

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

Step 4

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

$\frac{e^{\cos (x)} - (1 + x) (e^{\cos (x)} (- \sin (x)))}{e^{2 \cos (x)}}$

Step 5

Multiply.

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Step 5.1

Multiply $- 1$ by $- 1$ .

$\frac{e^{\cos (x)} + 1 (1 + x) (e^{\cos (x)} (\sin (x)))}{e^{2 \cos (x)}}$

Step 5.2

Multiply $1 + x$ by $1$ .

$\frac{e^{\cos (x)} + (1 + x) (e^{\cos (x)} (\sin (x)))}{e^{2 \cos (x)}}$

Step 6

Simplify.

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Step 6.1

Apply the distributive property.

$\frac{e^{\cos (x)} + (1 e^{\cos (x)} + x e^{\cos (x)}) \sin (x)}{e^{2 \cos (x)}}$

Step 6.2

Apply the distributive property.

$\frac{e^{\cos (x)} + 1 e^{\cos (x)} \sin (x) + x e^{\cos (x)} \sin (x)}{e^{2 \cos (x)}}$

Step 6.3

Multiply $e^{\cos (x)}$ by $1$ .

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

Step 6.4

Reorder terms.

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