Calculus Examples

$f (x) = \frac{e^{x}}{9 x^{2} + 1}$

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 $f (x) = e^{x}$ and $g (x) = 9 x^{2} + 1$ .

$\frac{(9 x^{2} + 1) \frac{d}{d x} [e^{x}] - e^{x} \frac{d}{d x} [9 x^{2} + 1]}{{(9 x^{2} + 1)}^{2}}$

Step 2

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

$\frac{(9 x^{2} + 1) e^{x} - e^{x} \frac{d}{d x} [9 x^{2} + 1]}{{(9 x^{2} + 1)}^{2}}$

Step 3

Differentiate.

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Step 3.1

By the Sum Rule, the derivative of $9 x^{2} + 1$ with respect to $x$ is $\frac{d}{d x} [9 x^{2}] + \frac{d}{d x} [1]$ .

$\frac{(9 x^{2} + 1) e^{x} - e^{x} (\frac{d}{d x} [9 x^{2}] + \frac{d}{d x} [1])}{{(9 x^{2} + 1)}^{2}}$

Step 3.2

Since $9$ is constant with respect to $x$ , the derivative of $9 x^{2}$ with respect to $x$ is $9 \frac{d}{d x} [x^{2}]$ .

$\frac{(9 x^{2} + 1) e^{x} - e^{x} (9 \frac{d}{d x} [x^{2}] + \frac{d}{d x} [1])}{{(9 x^{2} + 1)}^{2}}$

Step 3.3

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

$\frac{(9 x^{2} + 1) e^{x} - e^{x} (9 (2 x) + \frac{d}{d x} [1])}{{(9 x^{2} + 1)}^{2}}$

Step 3.4

Multiply $2$ by $9$ .

$\frac{(9 x^{2} + 1) e^{x} - e^{x} (18 x + \frac{d}{d x} [1])}{{(9 x^{2} + 1)}^{2}}$

Step 3.5

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

$\frac{(9 x^{2} + 1) e^{x} - e^{x} (18 x + 0)}{{(9 x^{2} + 1)}^{2}}$

Step 3.6

Simplify the expression.

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Step 3.6.1

Add $18 x$ and $0$ .

$\frac{(9 x^{2} + 1) e^{x} - e^{x} (18 x)}{{(9 x^{2} + 1)}^{2}}$

Step 3.6.2

Multiply $18$ by $- 1$ .

$\frac{(9 x^{2} + 1) e^{x} - 18 e^{x} x}{{(9 x^{2} + 1)}^{2}}$

Step 4

Simplify.

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Step 4.1

Apply the distributive property.

$\frac{9 x^{2} e^{x} + 1 e^{x} - 18 e^{x} x}{{(9 x^{2} + 1)}^{2}}$

Step 4.2

Simplify the numerator.

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Step 4.2.1

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

$\frac{9 x^{2} e^{x} + e^{x} - 18 e^{x} x}{{(9 x^{2} + 1)}^{2}}$

Step 4.2.2

Reorder factors in $9 x^{2} e^{x} + e^{x} - 18 e^{x} x$ .

$\frac{9 x^{2} e^{x} + e^{x} - 18 x e^{x}}{{(9 x^{2} + 1)}^{2}}$

Step 4.3

Reorder terms.

$\frac{9 e^{x} x^{2} - 18 e^{x} x + e^{x}}{{(9 x^{2} + 1)}^{2}}$

Step 4.4

Factor $e^{x}$ out of $9 e^{x} x^{2} - 18 e^{x} x + e^{x}$ .

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Step 4.4.1

Factor $e^{x}$ out of $9 e^{x} x^{2}$ .

$\frac{e^{x} (9 x^{2}) - 18 e^{x} x + e^{x}}{{(9 x^{2} + 1)}^{2}}$

Step 4.4.2

Factor $e^{x}$ out of $- 18 e^{x} x$ .

$\frac{e^{x} (9 x^{2}) + e^{x} (- 18 x) + e^{x}}{{(9 x^{2} + 1)}^{2}}$

Step 4.4.3

Multiply by $1$ .

$\frac{e^{x} (9 x^{2}) + e^{x} (- 18 x) + e^{x} \cdot 1}{{(9 x^{2} + 1)}^{2}}$

Step 4.4.4

Factor $e^{x}$ out of $e^{x} (9 x^{2}) + e^{x} (- 18 x)$ .

$\frac{e^{x} (9 x^{2} - 18 x) + e^{x} \cdot 1}{{(9 x^{2} + 1)}^{2}}$

Step 4.4.5

Factor $e^{x}$ out of $e^{x} (9 x^{2} - 18 x) + e^{x} \cdot 1$ .

$\frac{e^{x} (9 x^{2} - 18 x + 1)}{{(9 x^{2} + 1)}^{2}}$