Calculus Examples

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

Step 1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{3 + x^{2}}$ as ${(3 + x^{2})}^{\frac{1}{2}}$ .

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

Step 2

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = \ln (x)$ and $g (x) = x + {(3 + x^{2})}^{\frac{1}{2}}$ .

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Step 2.1

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

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

Step 2.2

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

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

Step 2.3

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

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

Step 3

Differentiate.

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Step 3.1

By the Sum Rule, the derivative of $x + {(3 + x^{2})}^{\frac{1}{2}}$ with respect to $x$ is $\frac{d}{d x} [x] + \frac{d}{d x} [{(3 + x^{2})}^{\frac{1}{2}}]$ .

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

Step 3.2

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

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

Step 4

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 $g (x) = 3 + x^{2}$ .

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Step 4.1

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

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

Step 4.2

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

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

Step 4.3

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

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

Step 5

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

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

Step 6

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

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

Step 7

Combine the numerators over the common denominator.

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

Step 8

Simplify the numerator.

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Step 8.1

Multiply $- 1$ by $2$ .

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

Step 8.2

Subtract $2$ from $1$ .

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

Step 9

Combine fractions.

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Step 9.1

Move the negative in front of the fraction.

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

Step 9.2

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

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

Step 9.3

Move ${(3 + x^{2})}^{- \frac{1}{2}}$ to the denominator using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

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

Step 10

By the Sum Rule, the derivative of $3 + x^{2}$ with respect to $x$ is $\frac{d}{d x} [3] + \frac{d}{d x} [x^{2}]$ .

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

Step 11

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

$\frac{1}{x + {(3 + x^{2})}^{\frac{1}{2}}} (1 + \frac{1}{2 {(3 + x^{2})}^{\frac{1}{2}}} (0 + \frac{d}{d x} [x^{2}]))$

Step 12

Add $0$ and $\frac{d}{d x} [x^{2}]$ .

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

Step 13

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

$\frac{1}{x + {(3 + x^{2})}^{\frac{1}{2}}} (1 + \frac{1}{2 {(3 + x^{2})}^{\frac{1}{2}}} (2 x))$

Step 14

Simplify terms.

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Step 14.1

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

$\frac{1}{x + {(3 + x^{2})}^{\frac{1}{2}}} (1 + \frac{2}{2 {(3 + x^{2})}^{\frac{1}{2}}} x)$

Step 14.2

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

$\frac{1}{x + {(3 + x^{2})}^{\frac{1}{2}}} (1 + \frac{2 x}{2 {(3 + x^{2})}^{\frac{1}{2}}})$

Step 14.3

Cancel the common factor.

$\frac{1}{x + {(3 + x^{2})}^{\frac{1}{2}}} (1 + \frac{2 x}{2 {(3 + x^{2})}^{\frac{1}{2}}})$

Step 14.4

Rewrite the expression.

$\frac{1}{x + {(3 + x^{2})}^{\frac{1}{2}}} (1 + \frac{x}{{(3 + x^{2})}^{\frac{1}{2}}})$

Step 15

Simplify.

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Step 15.1

Reorder the factors of $\frac{1}{x + {(3 + x^{2})}^{\frac{1}{2}}} (1 + \frac{x}{{(3 + x^{2})}^{\frac{1}{2}}})$ .

$(1 + \frac{x}{{(3 + x^{2})}^{\frac{1}{2}}}) \frac{1}{x + {(3 + x^{2})}^{\frac{1}{2}}}$

Step 15.2

Multiply $1 + \frac{x}{{(3 + x^{2})}^{\frac{1}{2}}}$ by $\frac{1}{x + {(3 + x^{2})}^{\frac{1}{2}}}$ .

$\frac{1 + \frac{x}{{(3 + x^{2})}^{\frac{1}{2}}}}{x + {(3 + x^{2})}^{\frac{1}{2}}}$

Step 15.3

Multiply the numerator and denominator of the fraction by ${(3 + x^{2})}^{\frac{1}{2}}$ .

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Step 15.3.1

Multiply $\frac{1 + \frac{x}{{(3 + x^{2})}^{\frac{1}{2}}}}{x + {(3 + x^{2})}^{\frac{1}{2}}}$ by $\frac{{(3 + x^{2})}^{\frac{1}{2}}}{{(3 + x^{2})}^{\frac{1}{2}}}$ .

$\frac{{(3 + x^{2})}^{\frac{1}{2}}}{{(3 + x^{2})}^{\frac{1}{2}}} \cdot \frac{1 + \frac{x}{{(3 + x^{2})}^{\frac{1}{2}}}}{x + {(3 + x^{2})}^{\frac{1}{2}}}$

Step 15.3.2

Combine.

$\frac{{(3 + x^{2})}^{\frac{1}{2}} (1 + \frac{x}{{(3 + x^{2})}^{\frac{1}{2}}})}{{(3 + x^{2})}^{\frac{1}{2}} (x + {(3 + x^{2})}^{\frac{1}{2}})}$

Step 15.4

Apply the distributive property.

$\frac{{(3 + x^{2})}^{\frac{1}{2}} \cdot 1 + {(3 + x^{2})}^{\frac{1}{2}} \frac{x}{{(3 + x^{2})}^{\frac{1}{2}}}}{{(3 + x^{2})}^{\frac{1}{2}} x + {(3 + x^{2})}^{\frac{1}{2}} {(3 + x^{2})}^{\frac{1}{2}}}$

Step 15.5

Cancel the common factor of ${(3 + x^{2})}^{\frac{1}{2}}$ .

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Step 15.5.1

Cancel the common factor.

Step 15.5.2

Rewrite the expression.

$\frac{{(3 + x^{2})}^{\frac{1}{2}} \cdot 1 + x}{{(3 + x^{2})}^{\frac{1}{2}} x + {(3 + x^{2})}^{\frac{1}{2}} {(3 + x^{2})}^{\frac{1}{2}}}$

Step 15.6

Multiply ${(3 + x^{2})}^{\frac{1}{2}}$ by $1$ .

$\frac{{(3 + x^{2})}^{\frac{1}{2}} + x}{{(3 + x^{2})}^{\frac{1}{2}} x + {(3 + x^{2})}^{\frac{1}{2}} {(3 + x^{2})}^{\frac{1}{2}}}$

Step 15.7

Simplify the denominator.

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Step 15.7.1

Multiply ${(3 + x^{2})}^{\frac{1}{2}}$ by ${(3 + x^{2})}^{\frac{1}{2}}$ by adding the exponents.

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Step 15.7.1.1

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

$\frac{{(3 + x^{2})}^{\frac{1}{2}} + x}{{(3 + x^{2})}^{\frac{1}{2}} x + {(3 + x^{2})}^{\frac{1}{2} + \frac{1}{2}}}$

Step 15.7.1.2

Combine the numerators over the common denominator.

$\frac{{(3 + x^{2})}^{\frac{1}{2}} + x}{{(3 + x^{2})}^{\frac{1}{2}} x + {(3 + x^{2})}^{\frac{1 + 1}{2}}}$

Step 15.7.1.3

Add $1$ and $1$ .

$\frac{{(3 + x^{2})}^{\frac{1}{2}} + x}{{(3 + x^{2})}^{\frac{1}{2}} x + {(3 + x^{2})}^{\frac{2}{2}}}$

Step 15.7.1.4

Divide $2$ by $2$ .

$\frac{{(3 + x^{2})}^{\frac{1}{2}} + x}{{(3 + x^{2})}^{\frac{1}{2}} x + {(3 + x^{2})}^{1}}$

Step 15.7.2

Simplify ${(3 + x^{2})}^{1}$ .

$\frac{{(3 + x^{2})}^{\frac{1}{2}} + x}{{(3 + x^{2})}^{\frac{1}{2}} x + 3 + x^{2}}$

Step 15.7.3

Reorder terms.

$\frac{{(3 + x^{2})}^{\frac{1}{2}} + x}{x^{2} + x {(3 + x^{2})}^{\frac{1}{2}} + 3}$