Calculus Examples

$\frac{1 - e^{x}}{1 + e^{x}}$

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

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

Step 2

Differentiate.

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Step 2.1

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

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

Step 2.2

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

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

Step 2.3

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

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

Step 2.4

Since $- 1$ is constant with respect to $x$ , the derivative of $- e^{x}$ with respect to $x$ is $- \frac{d}{d x} [e^{x}]$ .

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

Step 3

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

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

Step 4

Differentiate.

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Step 4.1

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

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

Step 4.2

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

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

Step 4.3

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

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

Step 5

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

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

Step 6

Simplify.

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Step 6.1

Apply the distributive property.

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

Step 6.2

Apply the distributive property.

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

Step 6.3

Apply the distributive property.

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

Step 6.4

Simplify the numerator.

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Step 6.4.1

Simplify each term.

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Step 6.4.1.1

Multiply $- e^{x}$ by $1$ .

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

Step 6.4.1.2

Rewrite using the commutative property of multiplication.

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

Step 6.4.1.3

Multiply $e^{x}$ by $e^{x}$ by adding the exponents.

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Step 6.4.1.3.1

Move $e^{x}$ .

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

Step 6.4.1.3.2

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

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

Step 6.4.1.3.3

Add $x$ and $x$ .

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

Step 6.4.1.4

Multiply $- 1$ by $1$ .

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

Step 6.4.1.5

Rewrite $- 1 e^{x}$ as $- e^{x}$ .

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

Step 6.4.1.6

Multiply $e^{x}$ by $e^{x}$ by adding the exponents.

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Step 6.4.1.6.1

Move $e^{x}$ .

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

Step 6.4.1.6.2

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

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

Step 6.4.1.6.3

Add $x$ and $x$ .

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

Step 6.4.1.7

Multiply $- - e^{2 x}$ .

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Step 6.4.1.7.1

Multiply $- 1$ by $- 1$ .

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

Step 6.4.1.7.2

Multiply $e^{2 x}$ by $1$ .

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

Step 6.4.2

Combine the opposite terms in $- e^{x} - e^{2 x} - e^{x} + e^{2 x}$ .

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Step 6.4.2.1

Add $- e^{2 x}$ and $e^{2 x}$ .

$\frac{- e^{x} + 0 - e^{x}}{{(1 + e^{x})}^{2}}$

Step 6.4.2.2

Add $- e^{x}$ and $0$ .

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

Step 6.4.3

Subtract $e^{x}$ from $- e^{x}$ .

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

Step 6.5

Move the negative in front of the fraction.

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