Calculus Examples

$f (x) = \frac{\sqrt{\ln (x)}}{x}$

Step 1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{\ln (x)}$ as ${\ln (x)}^{\frac{1}{2}}$ .

$\frac{d}{d x} [\frac{{\ln (x)}^{\frac{1}{2}}}{x}]$

Step 2

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 $f (x) = {\ln (x)}^{\frac{1}{2}}$ and $g (x) = x$ .

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

Step 3

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = x^{\frac{1}{2}}$ and $g (x) = \ln (x)$ .

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Step 3.1

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

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

Step 3.2

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

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

Step 3.3

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

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

Step 4

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{2}{2}$ .

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

Step 5

Combine $- 1$ and $\frac{2}{2}$ .

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

Step 6

Combine the numerators over the common denominator.

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

Step 7

Simplify the numerator.

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Step 7.1

Multiply $- 1$ by $2$ .

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

Step 7.2

Subtract $2$ from $1$ .

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

Step 8

Combine fractions.

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Step 8.1

Move the negative in front of the fraction.

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

Step 8.2

Combine $\frac{1}{2}$ and ${\ln (x)}^{- \frac{1}{2}}$ .

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

Step 8.3

Move ${\ln (x)}^{- \frac{1}{2}}$ to the denominator using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

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

Step 8.4

Combine $\frac{1}{2 {\ln (x)}^{\frac{1}{2}}}$ and $x$ .

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

Step 9

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

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

Step 10

Simplify terms.

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Step 10.1

Multiply $\frac{x}{2 {\ln (x)}^{\frac{1}{2}}}$ by $\frac{1}{x}$ .

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

Step 10.2

Cancel the common factor.

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

Step 10.3

Rewrite the expression.

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

Step 11

Multiply $\frac{\frac{1}{2 {\ln (x)}^{\frac{1}{2}}} - {\ln (x)}^{\frac{1}{2}} \frac{d}{d x} [x]}{x^{2}}$ by $\frac{2 {\ln (x)}^{\frac{1}{2}}}{2 {\ln (x)}^{\frac{1}{2}}}$ .

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

Step 12

Combine.

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

Step 13

Apply the distributive property.

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

Step 14

Cancel the common factor of $2 {\ln (x)}^{\frac{1}{2}}$ .

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Step 14.1

Cancel the common factor.

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

Step 14.2

Rewrite the expression.

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

Step 15

Multiply $- 1$ by $2$ .

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

Step 16

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

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

Step 17

Simplify the expression.

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Step 17.1

Combine the numerators over the common denominator.

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

Step 17.2

Add $1$ and $1$ .

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

Step 18

Cancel the common factor of $2$ .

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Step 18.1

Cancel the common factor.

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

Step 18.2

Rewrite the expression.

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

Step 19

Simplify.

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

Step 20

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

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

Step 21

Multiply $- 2$ by $1$ .

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

Step 22

Simplify.

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Step 22.1

Simplify $- 2 \ln (x)$ by moving $2$ inside the logarithm.

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

Step 22.2

Reorder terms.

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