Calculus Examples

$\frac{x^{2} + 14 x}{{(7 + x)}^{2}}$

Step 1

Differentiate using the Quotient Rule which states that $\frac{d}{d x} [\frac{f (x)}{g (x)}]$ is $\frac{g (x) \frac{d}{d x} [f (x)] - f (x) \frac{d}{d x} [g (x)]}{{g (x)}^{2}}$ where $f (x) = x^{2} + 14 x$ and $g (x) = {(7 + x)}^{2}$ .

$\frac{{(7 + x)}^{2} \frac{d}{d x} [x^{2} + 14 x] - (x^{2} + 14 x) \frac{d}{d x} [{(7 + x)}^{2}]}{{({(7 + x)}^{2})}^{2}}$

Step 2

Differentiate.

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Step 2.1

Multiply the exponents in ${({(7 + x)}^{2})}^{2}$ .

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Step 2.1.1

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

$\frac{{(7 + x)}^{2} \frac{d}{d x} [x^{2} + 14 x] - (x^{2} + 14 x) \frac{d}{d x} [{(7 + x)}^{2}]}{{(7 + x)}^{2 \cdot 2}}$

Step 2.1.2

Multiply $2$ by $2$ .

$\frac{{(7 + x)}^{2} \frac{d}{d x} [x^{2} + 14 x] - (x^{2} + 14 x) \frac{d}{d x} [{(7 + x)}^{2}]}{{(7 + x)}^{4}}$

Step 2.2

By the Sum Rule, the derivative of $x^{2} + 14 x$ with respect to $x$ is $\frac{d}{d x} [x^{2}] + \frac{d}{d x} [14 x]$ .

$\frac{{(7 + x)}^{2} (\frac{d}{d x} [x^{2}] + \frac{d}{d x} [14 x]) - (x^{2} + 14 x) \frac{d}{d x} [{(7 + x)}^{2}]}{{(7 + x)}^{4}}$

Step 2.3

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

$\frac{{(7 + x)}^{2} (2 x + \frac{d}{d x} [14 x]) - (x^{2} + 14 x) \frac{d}{d x} [{(7 + x)}^{2}]}{{(7 + x)}^{4}}$

Step 2.4

Since $14$ is constant with respect to $x$ , the derivative of $14 x$ with respect to $x$ is $14 \frac{d}{d x} [x]$ .

$\frac{{(7 + x)}^{2} (2 x + 14 \frac{d}{d x} [x]) - (x^{2} + 14 x) \frac{d}{d x} [{(7 + x)}^{2}]}{{(7 + x)}^{4}}$

Step 2.5

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

$\frac{{(7 + x)}^{2} (2 x + 14 \cdot 1) - (x^{2} + 14 x) \frac{d}{d x} [{(7 + x)}^{2}]}{{(7 + x)}^{4}}$

Step 2.6

Multiply $14$ by $1$ .

$\frac{{(7 + x)}^{2} (2 x + 14) - (x^{2} + 14 x) \frac{d}{d x} [{(7 + x)}^{2}]}{{(7 + x)}^{4}}$

Step 3

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = x^{2}$ and $g (x) = 7 + x$ .

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Step 3.1

To apply the Chain Rule, set $u$ as $7 + x$ .

$\frac{{(7 + x)}^{2} (2 x + 14) - (x^{2} + 14 x) (\frac{d}{d u} [u^{2}] \frac{d}{d x} [7 + x])}{{(7 + x)}^{4}}$

Step 3.2

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

$\frac{{(7 + x)}^{2} (2 x + 14) - (x^{2} + 14 x) (2 u \frac{d}{d x} [7 + x])}{{(7 + x)}^{4}}$

Step 3.3

Replace all occurrences of $u$ with $7 + x$ .

$\frac{{(7 + x)}^{2} (2 x + 14) - (x^{2} + 14 x) (2 (7 + x) \frac{d}{d x} [7 + x])}{{(7 + x)}^{4}}$

Step 4

Simplify with factoring out.

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Step 4.1

Multiply $2$ by $- 1$ .

$\frac{{(7 + x)}^{2} (2 x + 14) - 2 (x^{2} + 14 x) ((7 + x) \frac{d}{d x} [7 + x])}{{(7 + x)}^{4}}$

Step 4.2

Factor $7 + x$ out of ${(7 + x)}^{2} (2 x + 14) - 2 (x^{2} + 14 x) ((7 + x) \frac{d}{d x} [7 + x])$ .

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Step 4.2.1

Factor $7 + x$ out of ${(7 + x)}^{2} (2 x + 14)$ .

$\frac{(7 + x) ((7 + x) (2 x + 14)) - 2 (x^{2} + 14 x) ((7 + x) \frac{d}{d x} [7 + x])}{{(7 + x)}^{4}}$

Step 4.2.2

Factor $7 + x$ out of $- 2 (x^{2} + 14 x) ((7 + x) \frac{d}{d x} [7 + x])$ .

$\frac{(7 + x) ((7 + x) (2 x + 14)) + (7 + x) (- 2 (x^{2} + 14 x) (\frac{d}{d x} [7 + x]))}{{(7 + x)}^{4}}$

Step 4.2.3

Factor $7 + x$ out of $(7 + x) ((7 + x) (2 x + 14)) + (7 + x) (- 2 (x^{2} + 14 x) (\frac{d}{d x} [7 + x]))$ .

$\frac{(7 + x) ((7 + x) (2 x + 14) - 2 (x^{2} + 14 x) (\frac{d}{d x} [7 + x]))}{{(7 + x)}^{4}}$

Step 5

Cancel the common factors.

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Step 5.1

Factor $7 + x$ out of ${(7 + x)}^{4}$ .

$\frac{(7 + x) ((7 + x) (2 x + 14) - 2 (x^{2} + 14 x) (\frac{d}{d x} [7 + x]))}{(7 + x) {(7 + x)}^{3}}$

Step 5.2

Cancel the common factor.

$\frac{(7 + x) ((7 + x) (2 x + 14) - 2 (x^{2} + 14 x) (\frac{d}{d x} [7 + x]))}{(7 + x) {(7 + x)}^{3}}$

Step 5.3

Rewrite the expression.

$\frac{(7 + x) (2 x + 14) - 2 (x^{2} + 14 x) (\frac{d}{d x} [7 + x])}{{(7 + x)}^{3}}$

Step 6

By the Sum Rule, the derivative of $7 + x$ with respect to $x$ is $\frac{d}{d x} [7] + \frac{d}{d x} [x]$ .

$\frac{(7 + x) (2 x + 14) - 2 (x^{2} + 14 x) (\frac{d}{d x} [7] + \frac{d}{d x} [x])}{{(7 + x)}^{3}}$

Step 7

Since $7$ is constant with respect to $x$ , the derivative of $7$ with respect to $x$ is $0$ .

$\frac{(7 + x) (2 x + 14) - 2 (x^{2} + 14 x) (0 + \frac{d}{d x} [x])}{{(7 + x)}^{3}}$

Step 8

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

$\frac{(7 + x) (2 x + 14) - 2 (x^{2} + 14 x) \frac{d}{d x} [x]}{{(7 + x)}^{3}}$

Step 9

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

$\frac{(7 + x) (2 x + 14) - 2 (x^{2} + 14 x) \cdot 1}{{(7 + x)}^{3}}$

Step 10

Multiply $- 2$ by $1$ .

$\frac{(7 + x) (2 x + 14) - 2 (x^{2} + 14 x)}{{(7 + x)}^{3}}$

Step 11

Simplify.

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Step 11.1

Apply the distributive property.

$\frac{(7 + x) (2 x + 14) - 2 x^{2} - 2 (14 x)}{{(7 + x)}^{3}}$

Step 11.2

Simplify the numerator.

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Step 11.2.1

Simplify each term.

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Step 11.2.1.1

Expand $(7 + x) (2 x + 14)$ using the FOIL Method.

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Step 11.2.1.1.1

Apply the distributive property.

$\frac{7 (2 x + 14) + x (2 x + 14) - 2 x^{2} - 2 (14 x)}{{(7 + x)}^{3}}$

Step 11.2.1.1.2

Apply the distributive property.

$\frac{7 (2 x) + 7 \cdot 14 + x (2 x + 14) - 2 x^{2} - 2 (14 x)}{{(7 + x)}^{3}}$

Step 11.2.1.1.3

Apply the distributive property.

$\frac{7 (2 x) + 7 \cdot 14 + x (2 x) + x \cdot 14 - 2 x^{2} - 2 (14 x)}{{(7 + x)}^{3}}$

Step 11.2.1.2

Simplify and combine like terms.

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Step 11.2.1.2.1

Simplify each term.

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Step 11.2.1.2.1.1

Multiply $2$ by $7$ .

$\frac{14 x + 7 \cdot 14 + x (2 x) + x \cdot 14 - 2 x^{2} - 2 (14 x)}{{(7 + x)}^{3}}$

Step 11.2.1.2.1.2

Multiply $7$ by $14$ .

$\frac{14 x + 98 + x (2 x) + x \cdot 14 - 2 x^{2} - 2 (14 x)}{{(7 + x)}^{3}}$

Step 11.2.1.2.1.3

Rewrite using the commutative property of multiplication.

$\frac{14 x + 98 + 2 x \cdot x + x \cdot 14 - 2 x^{2} - 2 (14 x)}{{(7 + x)}^{3}}$

Step 11.2.1.2.1.4

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

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Step 11.2.1.2.1.4.1

Move $x$ .

$\frac{14 x + 98 + 2 (x \cdot x) + x \cdot 14 - 2 x^{2} - 2 (14 x)}{{(7 + x)}^{3}}$

Step 11.2.1.2.1.4.2

Multiply $x$ by $x$ .

$\frac{14 x + 98 + 2 x^{2} + x \cdot 14 - 2 x^{2} - 2 (14 x)}{{(7 + x)}^{3}}$

Step 11.2.1.2.1.5

Move $14$ to the left of $x$ .

$\frac{14 x + 98 + 2 x^{2} + 14 x - 2 x^{2} - 2 (14 x)}{{(7 + x)}^{3}}$

Step 11.2.1.2.2

Add $14 x$ and $14 x$ .

$\frac{28 x + 98 + 2 x^{2} - 2 x^{2} - 2 (14 x)}{{(7 + x)}^{3}}$

Step 11.2.1.3

Multiply $14$ by $- 2$ .

$\frac{28 x + 98 + 2 x^{2} - 2 x^{2} - 28 x}{{(7 + x)}^{3}}$

Step 11.2.2

Combine the opposite terms in $28 x + 98 + 2 x^{2} - 2 x^{2} - 28 x$ .

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Step 11.2.2.1

Subtract $2 x^{2}$ from $2 x^{2}$ .

$\frac{28 x + 98 + 0 - 28 x}{{(7 + x)}^{3}}$

Step 11.2.2.2

Add $28 x + 98$ and $0$ .

$\frac{28 x + 98 - 28 x}{{(7 + x)}^{3}}$

Step 11.2.2.3

Subtract $28 x$ from $28 x$ .

$\frac{0 + 98}{{(7 + x)}^{3}}$

Step 11.2.2.4

Add $0$ and $98$ .

$\frac{98}{{(7 + x)}^{3}}$

Step 11.3

Reorder terms.

$\frac{98}{{(x + 7)}^{3}}$