Calculus Examples

$x = \sqrt{1 + \cot (3 t)}$

Step 1

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

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

Step 2

Differentiate both sides of the equation.

$\frac{d}{d t} (x) = \frac{d}{d t} ({(1 + \cot (3 t))}^{\frac{1}{2}})$

Step 3

The derivative of $x$ with respect to $t$ is $x'$ .

$x'$

Step 4

Differentiate the right side of the equation.

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Step 4.1

Differentiate using the chain rule, which states that $\frac{d}{d t} [f (g (t))]$ is $f' (g (t)) g' (t)$ where $f (t) = t^{\frac{1}{2}}$ and $g (t) = 1 + \cot (3 t)$ .

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Step 4.1.1

To apply the Chain Rule, set $u_{1}$ as $1 + \cot (3 t)$ .

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

Step 4.1.2

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

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

Step 4.1.3

Replace all occurrences of $u_{1}$ with $1 + \cot (3 t)$ .

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

Step 4.2

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

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

Step 4.3

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

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

Step 4.4

Combine the numerators over the common denominator.

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

Step 4.5

Simplify the numerator.

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Step 4.5.1

Multiply $- 1$ by $2$ .

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

Step 4.5.2

Subtract $2$ from $1$ .

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

Step 4.6

Differentiate.

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Step 4.6.1

Move the negative in front of the fraction.

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

Step 4.6.2

Combine fractions.

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Step 4.6.2.1

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

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

Step 4.6.2.2

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

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

Step 4.6.3

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

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

Step 4.6.4

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

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

Step 4.6.5

Add $0$ and $\frac{d}{d t} [\cot (3 t)]$ .

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

Step 4.7

Differentiate using the chain rule, which states that $\frac{d}{d t} [f (g (t))]$ is $f' (g (t)) g' (t)$ where $f (t) = \cot (t)$ and $g (t) = 3 t$ .

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Step 4.7.1

To apply the Chain Rule, set $u_{2}$ as $3 t$ .

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

Step 4.7.2

The derivative of $\cot (u_{2})$ with respect to $u_{2}$ is $- \csc^{2} (u_{2})$ .

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

Step 4.7.3

Replace all occurrences of $u_{2}$ with $3 t$ .

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

Step 4.8

Differentiate.

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Step 4.8.1

Combine $\frac{1}{2 {(1 + \cot (3 t))}^{\frac{1}{2}}}$ and $\csc^{2} (3 t)$ .

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

Step 4.8.2

Since $3$ is constant with respect to $t$ , the derivative of $3 t$ with respect to $t$ is $3 \frac{d}{d t} [t]$ .

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

Step 4.8.3

Combine fractions.

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Step 4.8.3.1

Multiply $3$ by $- 1$ .

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

Step 4.8.3.2

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

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

Step 4.8.3.3

Move the negative in front of the fraction.

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

Step 4.8.4

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

$- \frac{3 \csc^{2} (3 t)}{2 {(1 + \cot (3 t))}^{\frac{1}{2}}} \cdot 1$

Step 4.8.5

Multiply $- 1$ by $1$ .

$- \frac{3 \csc^{2} (3 t)}{2 {(1 + \cot (3 t))}^{\frac{1}{2}}}$

Step 5

Reform the equation by setting the left side equal to the right side.

$x' = - \frac{3 \csc^{2} (3 t)}{2 {(1 + \cot (3 t))}^{\frac{1}{2}}}$

Step 6

Replace $x'$ with $\frac{d x}{d t}$ .

$\frac{d x}{d t} = - \frac{3 \csc^{2} (3 t)}{2 {(1 + \cot (3 t))}^{\frac{1}{2}}}$