Calculus Examples

$f (x) = {(4 x + 3)}^{2} \ln (4 x + 3)$

Step 1

Rewrite ${(4 x + 3)}^{2}$ as $(4 x + 3) (4 x + 3)$ .

$\frac{d}{d x} [(4 x + 3) (4 x + 3) \ln (4 x + 3)]$

Step 2

Expand $(4 x + 3) (4 x + 3)$ using the FOIL Method.

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Step 2.1

Apply the distributive property.

$\frac{d}{d x} [(4 x (4 x + 3) + 3 (4 x + 3)) \ln (4 x + 3)]$

Step 2.2

Apply the distributive property.

$\frac{d}{d x} [(4 x (4 x) + 4 x \cdot 3 + 3 (4 x + 3)) \ln (4 x + 3)]$

Step 2.3

Apply the distributive property.

$\frac{d}{d x} [(4 x (4 x) + 4 x \cdot 3 + 3 (4 x) + 3 \cdot 3) \ln (4 x + 3)]$

Step 3

Simplify and combine like terms.

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Step 3.1

Simplify each term.

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Step 3.1.1

Rewrite using the commutative property of multiplication.

$\frac{d}{d x} [(4 \cdot 4 x \cdot x + 4 x \cdot 3 + 3 (4 x) + 3 \cdot 3) \ln (4 x + 3)]$

Step 3.1.2

Multiply $x$ by $x$ by adding the exponents.

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Step 3.1.2.1

Move $x$ .

$\frac{d}{d x} [(4 \cdot 4 (x \cdot x) + 4 x \cdot 3 + 3 (4 x) + 3 \cdot 3) \ln (4 x + 3)]$

Step 3.1.2.2

Multiply $x$ by $x$ .

$\frac{d}{d x} [(4 \cdot 4 x^{2} + 4 x \cdot 3 + 3 (4 x) + 3 \cdot 3) \ln (4 x + 3)]$

Step 3.1.3

Multiply $4$ by $4$ .

$\frac{d}{d x} [(16 x^{2} + 4 x \cdot 3 + 3 (4 x) + 3 \cdot 3) \ln (4 x + 3)]$

Step 3.1.4

Multiply $3$ by $4$ .

$\frac{d}{d x} [(16 x^{2} + 12 x + 3 (4 x) + 3 \cdot 3) \ln (4 x + 3)]$

Step 3.1.5

Multiply $4$ by $3$ .

$\frac{d}{d x} [(16 x^{2} + 12 x + 12 x + 3 \cdot 3) \ln (4 x + 3)]$

Step 3.1.6

Multiply $3$ by $3$ .

$\frac{d}{d x} [(16 x^{2} + 12 x + 12 x + 9) \ln (4 x + 3)]$

Step 3.2

Add $12 x$ and $12 x$ .

$\frac{d}{d x} [(16 x^{2} + 24 x + 9) \ln (4 x + 3)]$

Step 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 $f (x) = 16 x^{2} + 24 x + 9$ and $g (x) = \ln (4 x + 3)$ .

$(16 x^{2} + 24 x + 9) \frac{d}{d x} [\ln (4 x + 3)] + \ln (4 x + 3) \frac{d}{d x} [16 x^{2} + 24 x + 9]$

Step 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 $g (x) = 4 x + 3$ .

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Step 5.1

To apply the Chain Rule, set $u$ as $4 x + 3$ .

$(16 x^{2} + 24 x + 9) (\frac{d}{d u} [\ln (u)] \frac{d}{d x} [4 x + 3]) + \ln (4 x + 3) \frac{d}{d x} [16 x^{2} + 24 x + 9]$

Step 5.2

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

$(16 x^{2} + 24 x + 9) (\frac{1}{u} \frac{d}{d x} [4 x + 3]) + \ln (4 x + 3) \frac{d}{d x} [16 x^{2} + 24 x + 9]$

Step 5.3

Replace all occurrences of $u$ with $4 x + 3$ .

$(16 x^{2} + 24 x + 9) (\frac{1}{4 x + 3} \frac{d}{d x} [4 x + 3]) + \ln (4 x + 3) \frac{d}{d x} [16 x^{2} + 24 x + 9]$

Step 6

Differentiate.

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Step 6.1

By the Sum Rule, the derivative of $4 x + 3$ with respect to $x$ is $\frac{d}{d x} [4 x] + \frac{d}{d x} [3]$ .

$(16 x^{2} + 24 x + 9) \frac{1}{4 x + 3} (\frac{d}{d x} [4 x] + \frac{d}{d x} [3]) + \ln (4 x + 3) \frac{d}{d x} [16 x^{2} + 24 x + 9]$

Step 6.2

Since $4$ is constant with respect to $x$ , the derivative of $4 x$ with respect to $x$ is $4 \frac{d}{d x} [x]$ .

$(16 x^{2} + 24 x + 9) \frac{1}{4 x + 3} (4 \frac{d}{d x} [x] + \frac{d}{d x} [3]) + \ln (4 x + 3) \frac{d}{d x} [16 x^{2} + 24 x + 9]$

Step 6.3

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

$(16 x^{2} + 24 x + 9) \frac{1}{4 x + 3} (4 \cdot 1 + \frac{d}{d x} [3]) + \ln (4 x + 3) \frac{d}{d x} [16 x^{2} + 24 x + 9]$

Step 6.4

Multiply $4$ by $1$ .

$(16 x^{2} + 24 x + 9) \frac{1}{4 x + 3} (4 + \frac{d}{d x} [3]) + \ln (4 x + 3) \frac{d}{d x} [16 x^{2} + 24 x + 9]$

Step 6.5

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

$(16 x^{2} + 24 x + 9) \frac{1}{4 x + 3} (4 + 0) + \ln (4 x + 3) \frac{d}{d x} [16 x^{2} + 24 x + 9]$

Step 6.6

Combine fractions.

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Step 6.6.1

Add $4$ and $0$ .

$(16 x^{2} + 24 x + 9) \frac{1}{4 x + 3} \cdot 4 + \ln (4 x + 3) \frac{d}{d x} [16 x^{2} + 24 x + 9]$

Step 6.6.2

Combine $4$ and $\frac{1}{4 x + 3}$ .

$(16 x^{2} + 24 x + 9) \frac{4}{4 x + 3} + \ln (4 x + 3) \frac{d}{d x} [16 x^{2} + 24 x + 9]$

Step 6.7

By the Sum Rule, the derivative of $16 x^{2} + 24 x + 9$ with respect to $x$ is $\frac{d}{d x} [16 x^{2}] + \frac{d}{d x} [24 x] + \frac{d}{d x} [9]$ .

$(16 x^{2} + 24 x + 9) \frac{4}{4 x + 3} + \ln (4 x + 3) (\frac{d}{d x} [16 x^{2}] + \frac{d}{d x} [24 x] + \frac{d}{d x} [9])$

Step 6.8

Since $16$ is constant with respect to $x$ , the derivative of $16 x^{2}$ with respect to $x$ is $16 \frac{d}{d x} [x^{2}]$ .

$(16 x^{2} + 24 x + 9) \frac{4}{4 x + 3} + \ln (4 x + 3) (16 \frac{d}{d x} [x^{2}] + \frac{d}{d x} [24 x] + \frac{d}{d x} [9])$

Step 6.9

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

$(16 x^{2} + 24 x + 9) \frac{4}{4 x + 3} + \ln (4 x + 3) (16 (2 x) + \frac{d}{d x} [24 x] + \frac{d}{d x} [9])$

Step 6.10

Multiply $2$ by $16$ .

$(16 x^{2} + 24 x + 9) \frac{4}{4 x + 3} + \ln (4 x + 3) (32 x + \frac{d}{d x} [24 x] + \frac{d}{d x} [9])$

Step 6.11

Since $24$ is constant with respect to $x$ , the derivative of $24 x$ with respect to $x$ is $24 \frac{d}{d x} [x]$ .

$(16 x^{2} + 24 x + 9) \frac{4}{4 x + 3} + \ln (4 x + 3) (32 x + 24 \frac{d}{d x} [x] + \frac{d}{d x} [9])$

Step 6.12

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

$(16 x^{2} + 24 x + 9) \frac{4}{4 x + 3} + \ln (4 x + 3) (32 x + 24 \cdot 1 + \frac{d}{d x} [9])$

Step 6.13

Multiply $24$ by $1$ .

$(16 x^{2} + 24 x + 9) \frac{4}{4 x + 3} + \ln (4 x + 3) (32 x + 24 + \frac{d}{d x} [9])$

Step 6.14

Since $9$ is constant with respect to $x$ , the derivative of $9$ with respect to $x$ is $0$ .

$(16 x^{2} + 24 x + 9) \frac{4}{4 x + 3} + \ln (4 x + 3) (32 x + 24 + 0)$

Step 6.15

Add $32 x + 24$ and $0$ .

$(16 x^{2} + 24 x + 9) \frac{4}{4 x + 3} + \ln (4 x + 3) (32 x + 24)$

Step 7

Simplify.

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Step 7.1

Reorder terms.

$(16 x^{2} + 24 x + 9) \frac{4}{4 x + 3} + (32 x + 24) \ln (4 x + 3)$

Step 7.2

Simplify each term.

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Step 7.2.1

Multiply $16 x^{2} + 24 x + 9$ by $\frac{4}{4 x + 3}$ .

$\frac{(16 x^{2} + 24 x + 9) \cdot 4}{4 x + 3} + (32 x + 24) \ln (4 x + 3)$

Step 7.2.2

Factor using the perfect square rule.

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Step 7.2.2.1

Rewrite $16 x^{2}$ as ${(4 x)}^{2}$ .

$\frac{({(4 x)}^{2} + 24 x + 9) \cdot 4}{4 x + 3} + (32 x + 24) \ln (4 x + 3)$

Step 7.2.2.2

Rewrite $9$ as $3^{2}$ .

$\frac{({(4 x)}^{2} + 24 x + 3^{2}) \cdot 4}{4 x + 3} + (32 x + 24) \ln (4 x + 3)$

Step 7.2.2.3

Check that the middle term is two times the product of the numbers being squared in the first term and third term.

$24 x = 2 \cdot (4 x) \cdot 3$

Step 7.2.2.4

Rewrite the polynomial.

$\frac{({(4 x)}^{2} + 2 \cdot (4 x) \cdot 3 + 3^{2}) \cdot 4}{4 x + 3} + (32 x + 24) \ln (4 x + 3)$

Step 7.2.2.5

Factor using the perfect square trinomial rule $a^{2} + 2 a b + b^{2} = {(a + b)}^{2}$ , where $a = 4 x$ and $b = 3$ .

$\frac{{(4 x + 3)}^{2} \cdot 4}{4 x + 3} + (32 x + 24) \ln (4 x + 3)$

Step 7.2.3

Cancel the common factor of ${(4 x + 3)}^{2}$ and $4 x + 3$ .

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Step 7.2.3.1

Factor $4 x + 3$ out of ${(4 x + 3)}^{2} \cdot 4$ .

$\frac{(4 x + 3) ((4 x + 3) \cdot 4)}{4 x + 3} + (32 x + 24) \ln (4 x + 3)$

Step 7.2.3.2

Cancel the common factors.

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Step 7.2.3.2.1

Multiply by $1$ .

$\frac{(4 x + 3) ((4 x + 3) \cdot 4)}{(4 x + 3) \cdot 1} + (32 x + 24) \ln (4 x + 3)$

Step 7.2.3.2.2

Cancel the common factor.

$\frac{(4 x + 3) ((4 x + 3) \cdot 4)}{(4 x + 3) \cdot 1} + (32 x + 24) \ln (4 x + 3)$

Step 7.2.3.2.3

Rewrite the expression.

$\frac{(4 x + 3) \cdot 4}{1} + (32 x + 24) \ln (4 x + 3)$

Step 7.2.3.2.4

Divide $(4 x + 3) \cdot 4$ by $1$ .

$(4 x + 3) \cdot 4 + (32 x + 24) \ln (4 x + 3)$

Step 7.2.4

Apply the distributive property.

$4 x \cdot 4 + 3 \cdot 4 + (32 x + 24) \ln (4 x + 3)$

Step 7.2.5

Multiply $4$ by $4$ .

$16 x + 3 \cdot 4 + (32 x + 24) \ln (4 x + 3)$

Step 7.2.6

Multiply $3$ by $4$ .

$16 x + 12 + (32 x + 24) \ln (4 x + 3)$

Step 7.2.7

Apply the distributive property.

$16 x + 12 + 32 x \ln (4 x + 3) + 24 \ln (4 x + 3)$