Calculus Examples

$f (x) = (2 x - 1) (\ln (5 x + 1) + x^{2})$

Step 1

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 $f (x) = 2 x - 1$ and $g (x) = \ln (5 x + 1) + x^{2}$ .

$(2 x - 1) \frac{d}{d x} [\ln (5 x + 1) + x^{2}] + (\ln (5 x + 1) + x^{2}) \frac{d}{d x} [2 x - 1]$

Step 2

By the Sum Rule, the derivative of $\ln (5 x + 1) + x^{2}$ with respect to $x$ is $\frac{d}{d x} [\ln (5 x + 1)] + \frac{d}{d x} [x^{2}]$ .

$(2 x - 1) (\frac{d}{d x} [\ln (5 x + 1)] + \frac{d}{d x} [x^{2}]) + (\ln (5 x + 1) + x^{2}) \frac{d}{d x} [2 x - 1]$

Step 3

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = \ln (x)$ and $g (x) = 5 x + 1$ .

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Step 3.1

To apply the Chain Rule, set $u$ as $5 x + 1$ .

$(2 x - 1) (\frac{d}{d u} [\ln (u)] \frac{d}{d x} [5 x + 1] + \frac{d}{d x} [x^{2}]) + (\ln (5 x + 1) + x^{2}) \frac{d}{d x} [2 x - 1]$

Step 3.2

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

$(2 x - 1) (\frac{1}{u} \frac{d}{d x} [5 x + 1] + \frac{d}{d x} [x^{2}]) + (\ln (5 x + 1) + x^{2}) \frac{d}{d x} [2 x - 1]$

Step 3.3

Replace all occurrences of $u$ with $5 x + 1$ .

$(2 x - 1) (\frac{1}{5 x + 1} \frac{d}{d x} [5 x + 1] + \frac{d}{d x} [x^{2}]) + (\ln (5 x + 1) + x^{2}) \frac{d}{d x} [2 x - 1]$

Step 4

Differentiate.

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Step 4.1

By the Sum Rule, the derivative of $5 x + 1$ with respect to $x$ is $\frac{d}{d x} [5 x] + \frac{d}{d x} [1]$ .

$(2 x - 1) (\frac{1}{5 x + 1} (\frac{d}{d x} [5 x] + \frac{d}{d x} [1]) + \frac{d}{d x} [x^{2}]) + (\ln (5 x + 1) + x^{2}) \frac{d}{d x} [2 x - 1]$

Step 4.2

Since $5$ is constant with respect to $x$ , the derivative of $5 x$ with respect to $x$ is $5 \frac{d}{d x} [x]$ .

$(2 x - 1) (\frac{1}{5 x + 1} (5 \frac{d}{d x} [x] + \frac{d}{d x} [1]) + \frac{d}{d x} [x^{2}]) + (\ln (5 x + 1) + x^{2}) \frac{d}{d x} [2 x - 1]$

Step 4.3

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

$(2 x - 1) (\frac{1}{5 x + 1} (5 \cdot 1 + \frac{d}{d x} [1]) + \frac{d}{d x} [x^{2}]) + (\ln (5 x + 1) + x^{2}) \frac{d}{d x} [2 x - 1]$

Step 4.4

Multiply $5$ by $1$ .

$(2 x - 1) (\frac{1}{5 x + 1} (5 + \frac{d}{d x} [1]) + \frac{d}{d x} [x^{2}]) + (\ln (5 x + 1) + x^{2}) \frac{d}{d x} [2 x - 1]$

Step 4.5

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

$(2 x - 1) (\frac{1}{5 x + 1} (5 + 0) + \frac{d}{d x} [x^{2}]) + (\ln (5 x + 1) + x^{2}) \frac{d}{d x} [2 x - 1]$

Step 4.6

Combine fractions.

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Step 4.6.1

Add $5$ and $0$ .

$(2 x - 1) (\frac{1}{5 x + 1} \cdot 5 + \frac{d}{d x} [x^{2}]) + (\ln (5 x + 1) + x^{2}) \frac{d}{d x} [2 x - 1]$

Step 4.6.2

Combine $\frac{1}{5 x + 1}$ and $5$ .

$(2 x - 1) (\frac{5}{5 x + 1} + \frac{d}{d x} [x^{2}]) + (\ln (5 x + 1) + x^{2}) \frac{d}{d x} [2 x - 1]$

Step 4.7

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

$(2 x - 1) (\frac{5}{5 x + 1} + 2 x) + (\ln (5 x + 1) + x^{2}) \frac{d}{d x} [2 x - 1]$

Step 5

To write $2 x$ as a fraction with a common denominator, multiply by $\frac{5 x + 1}{5 x + 1}$ .

$(2 x - 1) (\frac{5}{5 x + 1} + \frac{2 x (5 x + 1)}{5 x + 1}) + (\ln (5 x + 1) + x^{2}) \frac{d}{d x} [2 x - 1]$

Step 6

Combine the numerators over the common denominator.

$(2 x - 1) \frac{5 + 2 x (5 x + 1)}{5 x + 1} + (\ln (5 x + 1) + x^{2}) \frac{d}{d x} [2 x - 1]$

Step 7

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

$(2 x - 1) \frac{5 + 2 x (5 x + 1)}{5 x + 1} + (\ln (5 x + 1) + x^{2}) (\frac{d}{d x} [2 x] + \frac{d}{d x} [- 1])$

Step 8

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

$(2 x - 1) \frac{5 + 2 x (5 x + 1)}{5 x + 1} + (\ln (5 x + 1) + x^{2}) (2 \frac{d}{d x} [x] + \frac{d}{d x} [- 1])$

Step 9

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

$(2 x - 1) \frac{5 + 2 x (5 x + 1)}{5 x + 1} + (\ln (5 x + 1) + x^{2}) (2 \cdot 1 + \frac{d}{d x} [- 1])$

Step 10

Multiply $2$ by $1$ .

$(2 x - 1) \frac{5 + 2 x (5 x + 1)}{5 x + 1} + (\ln (5 x + 1) + x^{2}) (2 + \frac{d}{d x} [- 1])$

Step 11

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

$(2 x - 1) \frac{5 + 2 x (5 x + 1)}{5 x + 1} + (\ln (5 x + 1) + x^{2}) (2 + 0)$

Step 12

Simplify the expression.

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Step 12.1

Add $2$ and $0$ .

$(2 x - 1) \frac{5 + 2 x (5 x + 1)}{5 x + 1} + (\ln (5 x + 1) + x^{2}) \cdot 2$

Step 12.2

Move $2$ to the left of $\ln (5 x + 1) + x^{2}$ .

$(2 x - 1) \frac{5 + 2 x (5 x + 1)}{5 x + 1} + 2 \cdot (\ln (5 x + 1) + x^{2})$

Step 13

Simplify.

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Step 13.1

Apply the distributive property.

$(2 x - 1) \frac{5 + 2 x (5 x) + 2 x \cdot 1}{5 x + 1} + 2 (\ln (5 x + 1) + x^{2})$

Step 13.2

Apply the distributive property.

$(2 x - 1) \frac{5 + 2 x (5 x) + 2 x \cdot 1}{5 x + 1} + 2 \ln (5 x + 1) + 2 x^{2}$

Step 13.3

Combine terms.

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Step 13.3.1

Multiply $5$ by $2$ .

$(2 x - 1) \frac{5 + 10 x \cdot x + 2 x \cdot 1}{5 x + 1} + 2 \ln (5 x + 1) + 2 x^{2}$

Step 13.3.2

Raise $x$ to the power of $1$ .

$(2 x - 1) \frac{5 + 10 (x^{1} x) + 2 x \cdot 1}{5 x + 1} + 2 \ln (5 x + 1) + 2 x^{2}$

Step 13.3.3

Raise $x$ to the power of $1$ .

$(2 x - 1) \frac{5 + 10 (x^{1} x^{1}) + 2 x \cdot 1}{5 x + 1} + 2 \ln (5 x + 1) + 2 x^{2}$

Step 13.3.4

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

$(2 x - 1) \frac{5 + 10 x^{1 + 1} + 2 x \cdot 1}{5 x + 1} + 2 \ln (5 x + 1) + 2 x^{2}$

Step 13.3.5

Add $1$ and $1$ .

$(2 x - 1) \frac{5 + 10 x^{2} + 2 x \cdot 1}{5 x + 1} + 2 \ln (5 x + 1) + 2 x^{2}$

Step 13.3.6

Multiply $2$ by $1$ .

$(2 x - 1) \frac{5 + 10 x^{2} + 2 x}{5 x + 1} + 2 \ln (5 x + 1) + 2 x^{2}$

Step 13.4

Reorder terms.

$2 x^{2} + (2 x - 1) \frac{5 + 10 x^{2} + 2 x}{5 x + 1} + 2 \ln (5 x + 1)$