Calculus Examples

$y = {(2 x + 1)}^{4 x}$

Step 1

Differentiate both sides of the equation.

$\frac{d}{d x} (y) = \frac{d}{d x} ({(2 x + 1)}^{4 x})$

Step 2

The derivative of $y$ with respect to $x$ is $y'$ .

$y'$

Step 3

Differentiate the right side of the equation.

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Step 3.1

Use the properties of logarithms to simplify the differentiation.

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Step 3.1.1

Rewrite ${(2 x + 1)}^{4 x}$ as $e^{\ln ({(2 x + 1)}^{4 x})}$ .

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

Step 3.1.2

Expand $\ln ({(2 x + 1)}^{4 x})$ by moving $4 x$ outside the logarithm.

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

Step 3.2

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = e^{x}$ and $g (x) = 4 x \ln (2 x + 1)$ .

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Step 3.2.1

To apply the Chain Rule, set $u_{1}$ as $4 x \ln (2 x + 1)$ .

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

Step 3.2.2

Differentiate using the Exponential Rule which states that $\frac{d}{d u_{1}} [a^{u_{1}}]$ is $a^{u_{1}} \ln (a)$ where $a$ = $e$ .

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

Step 3.2.3

Replace all occurrences of $u_{1}$ with $4 x \ln (2 x + 1)$ .

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

Step 3.3

Since $4$ is constant with respect to $x$ , the derivative of $4 x \ln (2 x + 1)$ with respect to $x$ is $4 \frac{d}{d x} [x \ln (2 x + 1)]$ .

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

Step 3.4

Differentiate using the Product Rule which states that $\frac{d}{d x} [f (x) g (x)]$ is $f (x) \frac{d}{d x} [g (x)] + g (x) \frac{d}{d x} [f (x)]$ where $f (x) = x$ and $g (x) = \ln (2 x + 1)$ .

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

Step 3.5

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 $g (x) = 2 x + 1$ .

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Step 3.5.1

To apply the Chain Rule, set $u_{2}$ as $2 x + 1$ .

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

Step 3.5.2

The derivative of $\ln (u_{2})$ with respect to $u_{2}$ is $\frac{1}{u_{2}}$ .

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

Step 3.5.3

Replace all occurrences of $u_{2}$ with $2 x + 1$ .

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

Step 3.6

Differentiate.

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Step 3.6.1

Combine $\frac{1}{2 x + 1}$ and $x$ .

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

Step 3.6.2

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

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

Step 3.6.3

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

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

Step 3.6.4

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

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

Step 3.6.5

Multiply $2$ by $1$ .

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

Step 3.6.6

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

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

Step 3.6.7

Combine fractions.

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Step 3.6.7.1

Add $2$ and $0$ .

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

Step 3.6.7.2

Combine $\frac{x}{2 x + 1}$ and $2$ .

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

Step 3.6.7.3

Move $2$ to the left of $x$ .

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

Step 3.6.8

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

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

Step 3.6.9

Multiply $\ln (2 x + 1)$ by $1$ .

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

Step 3.7

To write $\ln (2 x + 1)$ as a fraction with a common denominator, multiply by $\frac{2 x + 1}{2 x + 1}$ .

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

Step 3.8

Combine the numerators over the common denominator.

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

Step 3.9

Combine $4$ and $\frac{2 x + \ln (2 x + 1) (2 x + 1)}{2 x + 1}$ .

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

Step 3.10

Combine $e^{4 x \ln (2 x + 1)}$ and $\frac{4 (2 x + \ln (2 x + 1) (2 x + 1))}{2 x + 1}$ .

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

Step 3.11

Simplify.

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Step 3.11.1

Apply the distributive property.

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

Step 3.11.2

Simplify the numerator.

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Step 3.11.2.1

Simplify $4 \ln (2 x + 1)$ by moving $4$ inside the logarithm.

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

Step 3.11.2.2

Simplify each term.

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Step 3.11.2.2.1

Multiply $2$ by $4$ .

$\frac{e^{x \ln ({(2 x + 1)}^{4})} (8 x + 4 (\ln (2 x + 1) (2 x + 1)))}{2 x + 1}$

Step 3.11.2.2.2

Apply the distributive property.

$\frac{e^{x \ln ({(2 x + 1)}^{4})} (8 x + 4 (\ln (2 x + 1) (2 x) + \ln (2 x + 1) \cdot 1))}{2 x + 1}$

Step 3.11.2.2.3

Rewrite using the commutative property of multiplication.

$\frac{e^{x \ln ({(2 x + 1)}^{4})} (8 x + 4 (2 \ln (2 x + 1) x + \ln (2 x + 1) \cdot 1))}{2 x + 1}$

Step 3.11.2.2.4

Multiply $\ln (2 x + 1)$ by $1$ .

$\frac{e^{x \ln ({(2 x + 1)}^{4})} (8 x + 4 (2 \ln (2 x + 1) x + \ln (2 x + 1)))}{2 x + 1}$

Step 3.11.2.2.5

Simplify $2 \ln (2 x + 1)$ by moving $2$ inside the logarithm.

$\frac{e^{x \ln ({(2 x + 1)}^{4})} (8 x + 4 (\ln ({(2 x + 1)}^{2}) x + \ln (2 x + 1)))}{2 x + 1}$

Step 3.11.2.2.6

Apply the distributive property.

$\frac{e^{x \ln ({(2 x + 1)}^{4})} (8 x + 4 (\ln ({(2 x + 1)}^{2}) x) + 4 \ln (2 x + 1))}{2 x + 1}$

Step 3.11.2.2.7

Multiply $4 (\ln ({(2 x + 1)}^{2}) x)$ .

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Step 3.11.2.2.7.1

Reorder $\ln ({(2 x + 1)}^{2})$ and $4$ .

$\frac{e^{x \ln ({(2 x + 1)}^{4})} (8 x + 4 \cdot \ln ({(2 x + 1)}^{2}) x + 4 \ln (2 x + 1))}{2 x + 1}$

Step 3.11.2.2.7.2

Simplify $4 \cdot \ln ({(2 x + 1)}^{2})$ by moving $4$ inside the logarithm.

$\frac{e^{x \ln ({(2 x + 1)}^{4})} (8 x + \ln ({({(2 x + 1)}^{2})}^{4}) x + 4 \ln (2 x + 1))}{2 x + 1}$

Step 3.11.2.2.8

Simplify $4 \ln (2 x + 1)$ by moving $4$ inside the logarithm.

$\frac{e^{x \ln ({(2 x + 1)}^{4})} (8 x + \ln ({({(2 x + 1)}^{2})}^{4}) x + \ln ({(2 x + 1)}^{4}))}{2 x + 1}$

Step 3.11.2.2.9

Multiply the exponents in ${({(2 x + 1)}^{2})}^{4}$ .

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Step 3.11.2.2.9.1

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

$\frac{e^{x \ln ({(2 x + 1)}^{4})} (8 x + \ln ({(2 x + 1)}^{2 \cdot 4}) x + \ln ({(2 x + 1)}^{4}))}{2 x + 1}$

Step 3.11.2.2.9.2

Multiply $2$ by $4$ .

$\frac{e^{x \ln ({(2 x + 1)}^{4})} (8 x + \ln ({(2 x + 1)}^{8}) x + \ln ({(2 x + 1)}^{4}))}{2 x + 1}$

Step 3.11.2.3

Apply the distributive property.

$\frac{e^{x \ln ({(2 x + 1)}^{4})} (8 x) + e^{x \ln ({(2 x + 1)}^{4})} (\ln ({(2 x + 1)}^{8}) x) + e^{x \ln ({(2 x + 1)}^{4})} \ln ({(2 x + 1)}^{4})}{2 x + 1}$

Step 3.11.2.4

Rewrite using the commutative property of multiplication.

$\frac{8 e^{x \ln ({(2 x + 1)}^{4})} x + e^{x \ln ({(2 x + 1)}^{4})} (\ln ({(2 x + 1)}^{8}) x) + e^{x \ln ({(2 x + 1)}^{4})} \ln ({(2 x + 1)}^{4})}{2 x + 1}$

Step 3.11.2.5

Reorder factors in $8 e^{x \ln ({(2 x + 1)}^{4})} x + e^{x \ln ({(2 x + 1)}^{4})} (\ln ({(2 x + 1)}^{8}) x) + e^{x \ln ({(2 x + 1)}^{4})} \ln ({(2 x + 1)}^{4})$ .

$\frac{8 x e^{x \ln ({(2 x + 1)}^{4})} + x e^{x \ln ({(2 x + 1)}^{4})} \ln ({(2 x + 1)}^{8}) + e^{x \ln ({(2 x + 1)}^{4})} \ln ({(2 x + 1)}^{4})}{2 x + 1}$

Step 3.11.3

Reorder terms.

$\frac{8 e^{x \ln ({(2 x + 1)}^{4})} x + e^{x \ln ({(2 x + 1)}^{4})} x \ln ({(2 x + 1)}^{8}) + e^{x \ln ({(2 x + 1)}^{4})} \ln ({(2 x + 1)}^{4})}{2 x + 1}$

Step 4

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

$y' = \frac{8 e^{x \ln ({(2 x + 1)}^{4})} x + e^{x \ln ({(2 x + 1)}^{4})} x \ln ({(2 x + 1)}^{8}) + e^{x \ln ({(2 x + 1)}^{4})} \ln ({(2 x + 1)}^{4})}{2 x + 1}$

Step 5

Replace $y'$ with $\frac{d y}{d x}$ .

$\frac{d y}{d x} = \frac{8 e^{x \ln ({(2 x + 1)}^{4})} x + e^{x \ln ({(2 x + 1)}^{4})} x \ln ({(2 x + 1)}^{8}) + e^{x \ln ({(2 x + 1)}^{4})} \ln ({(2 x + 1)}^{4})}{2 x + 1}$