Calculus Examples

$\frac{x}{\ln (x)}$

Step 1

Find the first derivative.

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Step 1.1

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 $f (x) = x$ and $g (x) = \ln (x)$ .

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

Step 1.2

Differentiate using the Power Rule.

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Step 1.2.1

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

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

Step 1.2.2

Multiply $\ln (x)$ by $1$ .

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

Step 1.3

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

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

Step 1.4

Simplify terms.

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Step 1.4.1

Combine $\frac{1}{x}$ and $x$ .

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

Step 1.4.2

Cancel the common factor of $x$ .

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Step 1.4.2.1

Cancel the common factor.

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

Step 1.4.2.2

Rewrite the expression.

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

Step 1.4.3

Multiply $- 1$ by $1$ .

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

Step 2

Find the second derivative.

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Step 2.1

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

Step 2.2

Differentiate using the Sum Rule.

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Step 2.2.1

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

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Step 2.2.1.1

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

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

Step 2.2.1.2

Multiply $2$ by $2$ .

$\frac{\ln^{2} (x) \frac{d}{d x} [\ln (x) - 1] - (\ln (x) - 1) \frac{d}{d x} [\ln^{2} (x)]}{\ln^{4} (x)}$

Step 2.2.2

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

$\frac{\ln^{2} (x) (\frac{d}{d x} [\ln (x)] + \frac{d}{d x} [- 1]) - (\ln (x) - 1) \frac{d}{d x} [\ln^{2} (x)]}{\ln^{4} (x)}$

Step 2.3

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

$\frac{\ln^{2} (x) (\frac{1}{x} + \frac{d}{d x} [- 1]) - (\ln (x) - 1) \frac{d}{d x} [\ln^{2} (x)]}{\ln^{4} (x)}$

Step 2.4

Differentiate using the Constant Rule.

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Step 2.4.1

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

$\frac{\ln^{2} (x) (\frac{1}{x} + 0) - (\ln (x) - 1) \frac{d}{d x} [\ln^{2} (x)]}{\ln^{4} (x)}$

Step 2.4.2

Combine fractions.

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Step 2.4.2.1

Add $\frac{1}{x}$ and $0$ .

$\frac{\ln^{2} (x) \frac{1}{x} - (\ln (x) - 1) \frac{d}{d x} [\ln^{2} (x)]}{\ln^{4} (x)}$

Step 2.4.2.2

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

$\frac{\frac{\ln^{2} (x)}{x} - (\ln (x) - 1) \frac{d}{d x} [\ln^{2} (x)]}{\ln^{4} (x)}$

Step 2.5

Multiply $\frac{\frac{\ln^{2} (x)}{x} - (\ln (x) - 1) \frac{d}{d x} [\ln^{2} (x)]}{\ln^{4} (x)}$ by $\frac{x}{x}$ .

$\frac{x}{x} \cdot \frac{\frac{\ln^{2} (x)}{x} - (\ln (x) - 1) \frac{d}{d x} [\ln^{2} (x)]}{\ln^{4} (x)}$

Step 2.6

Simplify terms.

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Step 2.6.1

Combine.

$\frac{x (\frac{\ln^{2} (x)}{x} - (\ln (x) - 1) \frac{d}{d x} [\ln^{2} (x)])}{x \ln^{4} (x)}$

Step 2.6.2

Apply the distributive property.

$\frac{x \frac{\ln^{2} (x)}{x} + x (- (\ln (x) - 1) \frac{d}{d x} [\ln^{2} (x)])}{x \ln^{4} (x)}$

Step 2.6.3

Cancel the common factor of $x$ .

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Step 2.6.3.1

Cancel the common factor.

$\frac{x \frac{\ln^{2} (x)}{x} + x (- (\ln (x) - 1) \frac{d}{d x} [\ln^{2} (x)])}{x \ln^{4} (x)}$

Step 2.6.3.2

Rewrite the expression.

$\frac{\ln^{2} (x) + x (- (\ln (x) - 1) \frac{d}{d x} [\ln^{2} (x)])}{x \ln^{4} (x)}$

Step 2.7

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 $g (x) = \ln (x)$ .

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Step 2.7.1

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

$\frac{\ln^{2} (x) + x (- (\ln (x) - 1) (\frac{d}{d u} [u^{2}] \frac{d}{d x} [\ln (x)]))}{x \ln^{4} (x)}$

Step 2.7.2

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

$\frac{\ln^{2} (x) + x (- (\ln (x) - 1) (2 u \frac{d}{d x} [\ln (x)]))}{x \ln^{4} (x)}$

Step 2.7.3

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

$\frac{\ln^{2} (x) + x (- (\ln (x) - 1) (2 \ln (x) \frac{d}{d x} [\ln (x)]))}{x \ln^{4} (x)}$

Step 2.8

Multiply $2$ by $- 1$ .

$\frac{\ln^{2} (x) + x (- 2 (\ln (x) - 1) (\ln (x) \frac{d}{d x} [\ln (x)]))}{x \ln^{4} (x)}$

Step 2.9

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

$\frac{\ln^{2} (x) + x (- 2 (\ln (x) - 1) (\ln (x) \frac{1}{x}))}{x \ln^{4} (x)}$

Step 2.10

Simplify terms.

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Step 2.10.1

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

$\frac{\ln^{2} (x) + x (- 2 (\ln (x) - 1) \frac{\ln (x)}{x})}{x \ln^{4} (x)}$

Step 2.10.2

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

$\frac{\ln^{2} (x) + x (\frac{\ln (x) \cdot - 2}{x} (\ln (x) - 1))}{x \ln^{4} (x)}$

Step 2.10.3

Simplify the expression.

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Step 2.10.3.1

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

$\frac{\ln^{2} (x) + x (\frac{- 2 \cdot \ln (x)}{x} (\ln (x) - 1))}{x \ln^{4} (x)}$

Step 2.10.3.2

Move the negative in front of the fraction.

$\frac{\ln^{2} (x) + x (- \frac{2 \ln (x)}{x} (\ln (x) - 1))}{x \ln^{4} (x)}$

Step 2.10.4

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

$\frac{\ln^{2} (x) - \frac{x (2 \ln (x))}{x} (\ln (x) - 1)}{x \ln^{4} (x)}$

Step 2.10.5

Cancel the common factor of $x$ .

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Step 2.10.5.1

Cancel the common factor.

$\frac{\ln^{2} (x) - \frac{x (2 \ln (x))}{x} (\ln (x) - 1)}{x \ln^{4} (x)}$

Step 2.10.5.2

Divide $2 \ln (x)$ by $1$ .

$\frac{\ln^{2} (x) - (2 \ln (x)) (\ln (x) - 1)}{x \ln^{4} (x)}$

Step 2.10.6

Multiply $2$ by $- 1$ .

$\frac{\ln^{2} (x) - 2 \ln (x) (\ln (x) - 1)}{x \ln^{4} (x)}$

Step 2.11

Simplify.

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Step 2.11.1

Apply the distributive property.

$\frac{\ln^{2} (x) - 2 \ln (x) \ln (x) - 2 \ln (x) \cdot - 1}{x \ln^{4} (x)}$

Step 2.11.2

Simplify each term.

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Step 2.11.2.1

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

$\frac{\ln^{2} (x) - \ln (x^{2}) \ln (x) - 2 \ln (x) \cdot - 1}{x \ln^{4} (x)}$

Step 2.11.2.2

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

$\frac{\ln^{2} (x) - \ln (x^{2}) \ln (x) - \ln (x^{2}) \cdot - 1}{x \ln^{4} (x)}$

Step 2.11.2.3

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

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Step 2.11.2.3.1

Multiply $- 1$ by $- 1$ .

$\frac{\ln^{2} (x) - \ln (x^{2}) \ln (x) + 1 \ln (x^{2})}{x \ln^{4} (x)}$

Step 2.11.2.3.2

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

$\frac{\ln^{2} (x) - \ln (x^{2}) \ln (x) + \ln (x^{2})}{x \ln^{4} (x)}$

Step 2.11.3

Reorder terms.

$f'' (x) = \frac{\ln^{2} (x) - \ln (x) \ln (x^{2}) + \ln (x^{2})}{x \ln^{4} (x)}$