Calculus Examples

$\ln ({(3 + e^{x})}^{2})$

Step 1

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

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Step 1.1

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

$\frac{d}{d u_{1}} [\ln (u_{1})] \frac{d}{d x} [{(3 + e^{x})}^{2}]$

Step 1.2

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

$\frac{1}{u_{1}} \frac{d}{d x} [{(3 + e^{x})}^{2}]$

Step 1.3

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

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

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

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Step 2.1

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

$\frac{1}{{(3 + e^{x})}^{2}} (\frac{d}{d u_{2}} [{u_{2}}^{2}] \frac{d}{d x} [3 + e^{x}])$

Step 2.2

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

$\frac{1}{{(3 + e^{x})}^{2}} (2 u_{2} \frac{d}{d x} [3 + e^{x}])$

Step 2.3

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

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

Step 3

Differentiate.

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Step 3.1

Combine $2$ and $\frac{1}{{(3 + e^{x})}^{2}}$ .

$\frac{2}{{(3 + e^{x})}^{2}} ((3 + e^{x}) \frac{d}{d x} [3 + e^{x}])$

Step 3.2

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

$\frac{2}{{(3 + e^{x})}^{2}} ((3 + e^{x}) (\frac{d}{d x} [3] + \frac{d}{d x} [e^{x}]))$

Step 3.3

Since $3$ is constant with respect to $x$ , the derivative of $3$ with respect to $x$ is $0$ .

$\frac{2}{{(3 + e^{x})}^{2}} ((3 + e^{x}) (0 + \frac{d}{d x} [e^{x}]))$

Step 3.4

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

$\frac{2}{{(3 + e^{x})}^{2}} ((3 + e^{x}) \frac{d}{d x} [e^{x}])$

Step 4

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

$\frac{2}{{(3 + e^{x})}^{2}} ((3 + e^{x}) e^{x})$

Step 5

Combine fractions.

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Step 5.1

Combine $e^{x}$ and $\frac{2}{{(3 + e^{x})}^{2}}$ .

$\frac{e^{x} \cdot 2}{{(3 + e^{x})}^{2}} (3 + e^{x})$

Step 5.2

Move $2$ to the left of $e^{x}$ .

$\frac{2 \cdot e^{x}}{{(3 + e^{x})}^{2}} (3 + e^{x})$

Step 6

Simplify.

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Step 6.1

Reorder the factors of $\frac{2 e^{x}}{{(3 + e^{x})}^{2}} (3 + e^{x})$ .

$(3 + e^{x}) \frac{2 e^{x}}{{(3 + e^{x})}^{2}}$

Step 6.2

Cancel the common factor of $3 + e^{x}$ .

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Step 6.2.1

Factor $3 + e^{x}$ out of ${(3 + e^{x})}^{2}$ .

$(3 + e^{x}) \frac{2 e^{x}}{(3 + e^{x}) (3 + e^{x})}$

Step 6.2.2

Cancel the common factor.

$(3 + e^{x}) \frac{2 e^{x}}{(3 + e^{x}) (3 + e^{x})}$

Step 6.2.3

Rewrite the expression.

$\frac{2 e^{x}}{3 + e^{x}}$