Calculus Examples

$y = \frac{(x - 7) (x^{2} + 4 x)}{x^{3}}$

Step 1

Differentiate both sides of the equation.

$\frac{d}{d x} (y) = \frac{d}{d x} (\frac{(x - 7) (x^{2} + 4 x)}{x^{3}})$

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

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 $f (x) = (x - 7) (x^{2} + 4 x)$ and $g (x) = x^{3}$ .

$\frac{x^{3} \frac{d}{d x} [(x - 7) (x^{2} + 4 x)] - (x - 7) (x^{2} + 4 x) \frac{d}{d x} [x^{3}]}{{(x^{3})}^{2}}$

Step 3.2

Multiply the exponents in ${(x^{3})}^{2}$ .

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Step 3.2.1

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

$\frac{x^{3} \frac{d}{d x} [(x - 7) (x^{2} + 4 x)] - (x - 7) (x^{2} + 4 x) \frac{d}{d x} [x^{3}]}{x^{3 \cdot 2}}$

Step 3.2.2

Multiply $3$ by $2$ .

$\frac{x^{3} \frac{d}{d x} [(x - 7) (x^{2} + 4 x)] - (x - 7) (x^{2} + 4 x) \frac{d}{d x} [x^{3}]}{x^{6}}$

Step 3.3

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 $f (x) = x - 7$ and $g (x) = x^{2} + 4 x$ .

$\frac{x^{3} ((x - 7) \frac{d}{d x} [x^{2} + 4 x] + (x^{2} + 4 x) \frac{d}{d x} [x - 7]) - (x - 7) (x^{2} + 4 x) \frac{d}{d x} [x^{3}]}{x^{6}}$

Step 3.4

Differentiate.

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Step 3.4.1

By the Sum Rule, the derivative of $x^{2} + 4 x$ with respect to $x$ is $\frac{d}{d x} [x^{2}] + \frac{d}{d x} [4 x]$ .

$\frac{x^{3} ((x - 7) (\frac{d}{d x} [x^{2}] + \frac{d}{d x} [4 x]) + (x^{2} + 4 x) \frac{d}{d x} [x - 7]) - (x - 7) (x^{2} + 4 x) \frac{d}{d x} [x^{3}]}{x^{6}}$

Step 3.4.2

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

$\frac{x^{3} ((x - 7) (2 x + \frac{d}{d x} [4 x]) + (x^{2} + 4 x) \frac{d}{d x} [x - 7]) - (x - 7) (x^{2} + 4 x) \frac{d}{d x} [x^{3}]}{x^{6}}$

Step 3.4.3

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

$\frac{x^{3} ((x - 7) (2 x + 4 \frac{d}{d x} [x]) + (x^{2} + 4 x) \frac{d}{d x} [x - 7]) - (x - 7) (x^{2} + 4 x) \frac{d}{d x} [x^{3}]}{x^{6}}$

Step 3.4.4

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

$\frac{x^{3} ((x - 7) (2 x + 4 \cdot 1) + (x^{2} + 4 x) \frac{d}{d x} [x - 7]) - (x - 7) (x^{2} + 4 x) \frac{d}{d x} [x^{3}]}{x^{6}}$

Step 3.4.5

Multiply $4$ by $1$ .

$\frac{x^{3} ((x - 7) (2 x + 4) + (x^{2} + 4 x) \frac{d}{d x} [x - 7]) - (x - 7) (x^{2} + 4 x) \frac{d}{d x} [x^{3}]}{x^{6}}$

Step 3.4.6

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

$\frac{x^{3} ((x - 7) (2 x + 4) + (x^{2} + 4 x) (\frac{d}{d x} [x] + \frac{d}{d x} [- 7])) - (x - 7) (x^{2} + 4 x) \frac{d}{d x} [x^{3}]}{x^{6}}$

Step 3.4.7

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

$\frac{x^{3} ((x - 7) (2 x + 4) + (x^{2} + 4 x) (1 + \frac{d}{d x} [- 7])) - (x - 7) (x^{2} + 4 x) \frac{d}{d x} [x^{3}]}{x^{6}}$

Step 3.4.8

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

$\frac{x^{3} ((x - 7) (2 x + 4) + (x^{2} + 4 x) (1 + 0)) - (x - 7) (x^{2} + 4 x) \frac{d}{d x} [x^{3}]}{x^{6}}$

Step 3.4.9

Simplify the expression.

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Step 3.4.9.1

Add $1$ and $0$ .

$\frac{x^{3} ((x - 7) (2 x + 4) + (x^{2} + 4 x) \cdot 1) - (x - 7) (x^{2} + 4 x) \frac{d}{d x} [x^{3}]}{x^{6}}$

Step 3.4.9.2

Multiply $x^{2} + 4 x$ by $1$ .

$\frac{x^{3} ((x - 7) (2 x + 4) + x^{2} + 4 x) - (x - 7) (x^{2} + 4 x) \frac{d}{d x} [x^{3}]}{x^{6}}$

Step 3.4.10

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 3$ .

$\frac{x^{3} ((x - 7) (2 x + 4) + x^{2} + 4 x) - (x - 7) (x^{2} + 4 x) (3 x^{2})}{x^{6}}$

Step 3.4.11

Simplify with factoring out.

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Step 3.4.11.1

Multiply $3$ by $- 1$ .

$\frac{x^{3} ((x - 7) (2 x + 4) + x^{2} + 4 x) - 3 (x - 7) (x^{2} + 4 x) x^{2}}{x^{6}}$

Step 3.4.11.2

Factor $x^{2}$ out of $x^{3} ((x - 7) (2 x + 4) + x^{2} + 4 x) - 3 (x - 7) (x^{2} + 4 x) x^{2}$ .

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Step 3.4.11.2.1

Factor $x^{2}$ out of $x^{3} ((x - 7) (2 x + 4) + x^{2} + 4 x)$ .

$\frac{x^{2} (x ((x - 7) (2 x + 4) + x^{2} + 4 x)) - 3 (x - 7) (x^{2} + 4 x) x^{2}}{x^{6}}$

Step 3.4.11.2.2

Factor $x^{2}$ out of $- 3 (x - 7) (x^{2} + 4 x) x^{2}$ .

$\frac{x^{2} (x ((x - 7) (2 x + 4) + x^{2} + 4 x)) + x^{2} (- 3 (x - 7) (1 + 4 x^{- 1}) x^{2})}{x^{6}}$

Step 3.4.11.2.3

Factor $x^{2}$ out of $x^{2} (x ((x - 7) (2 x + 4) + x^{2} + 4 x)) + x^{2} (- 3 (x - 7) (1 + 4 x^{- 1}) x^{2})$ .

$\frac{x^{2} (x ((x - 7) (2 x + 4) + x^{2} + 4 x) - 3 (x - 7) (1 + 4 x^{- 1}) x^{2})}{x^{6}}$

Step 3.5

Cancel the common factors.

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Step 3.5.1

Factor $x^{2}$ out of $x^{6}$ .

$\frac{x^{2} (x ((x - 7) (2 x + 4) + x^{2} + 4 x) - 3 (x - 7) (1 + 4 x^{- 1}) x^{2})}{x^{2} x^{4}}$

Step 3.5.2

Cancel the common factor.

$\frac{x^{2} (x ((x - 7) (2 x + 4) + x^{2} + 4 x) - 3 (x - 7) (1 + 4 x^{- 1}) x^{2})}{x^{2} x^{4}}$

Step 3.5.3

Rewrite the expression.

$\frac{x ((x - 7) (2 x + 4) + x^{2} + 4 x) - 3 (x - 7) (1 + 4 x^{- 1}) x^{2}}{x^{4}}$

Step 3.6

Factor $x$ out of $x ((x - 7) (2 x + 4) + x^{2} + 4 x) - 3 (x - 7) (1 + 4 x^{- 1}) x^{2}$ .

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Step 3.6.1

Factor $x$ out of $- 3 (x - 7) (1 + 4 x^{- 1}) x^{2}$ .

$\frac{x ((x - 7) (2 x + 4) + x^{2} + 4 x) + x (- 3 (x - 7) (1 + 4 x^{- 1}) x)}{x^{4}}$

Step 3.6.2

Factor $x$ out of $x ((x - 7) (2 x + 4) + x^{2} + 4 x) + x (- 3 (x - 7) (1 + 4 x^{- 1}) x)$ .

$\frac{x ((x - 7) (2 x + 4) + x^{2} + 4 x - 3 (x - 7) (1 + 4 x^{- 1}) x)}{x^{4}}$

Step 3.7

Cancel the common factors.

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Step 3.7.1

Factor $x$ out of $x^{4}$ .

$\frac{x ((x - 7) (2 x + 4) + x^{2} + 4 x - 3 (x - 7) (1 + 4 x^{- 1}) x)}{x \cdot x^{3}}$

Step 3.7.2

Cancel the common factor.

$\frac{x ((x - 7) (2 x + 4) + x^{2} + 4 x - 3 (x - 7) (1 + 4 x^{- 1}) x)}{x \cdot x^{3}}$

Step 3.7.3

Rewrite the expression.

$\frac{(x - 7) (2 x + 4) + x^{2} + 4 x - 3 (x - 7) (1 + 4 x^{- 1}) x}{x^{3}}$

Step 3.8

Simplify.

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Step 3.8.1

Rewrite the expression using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$\frac{(x - 7) (2 x + 4) + x^{2} + 4 x - 3 (x - 7) (1 + 4 \frac{1}{x}) x}{x^{3}}$

Step 3.8.2

Apply the distributive property.

$\frac{(x - 7) (2 x + 4) + x^{2} + 4 x + (- 3 x - 3 \cdot - 7) (1 + 4 \frac{1}{x}) x}{x^{3}}$

Step 3.8.3

Simplify the numerator.

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Step 3.8.3.1

Simplify each term.

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Step 3.8.3.1.1

Expand $(x - 7) (2 x + 4)$ using the FOIL Method.

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Step 3.8.3.1.1.1

Apply the distributive property.

$\frac{x (2 x + 4) - 7 (2 x + 4) + x^{2} + 4 x + (- 3 x - 3 \cdot - 7) (1 + 4 \frac{1}{x}) x}{x^{3}}$

Step 3.8.3.1.1.2

Apply the distributive property.

$\frac{x (2 x) + x \cdot 4 - 7 (2 x + 4) + x^{2} + 4 x + (- 3 x - 3 \cdot - 7) (1 + 4 \frac{1}{x}) x}{x^{3}}$

Step 3.8.3.1.1.3

Apply the distributive property.

$\frac{x (2 x) + x \cdot 4 - 7 (2 x) - 7 \cdot 4 + x^{2} + 4 x + (- 3 x - 3 \cdot - 7) (1 + 4 \frac{1}{x}) x}{x^{3}}$

Step 3.8.3.1.2

Simplify and combine like terms.

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Step 3.8.3.1.2.1

Simplify each term.

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Step 3.8.3.1.2.1.1

Rewrite using the commutative property of multiplication.

$\frac{2 x \cdot x + x \cdot 4 - 7 (2 x) - 7 \cdot 4 + x^{2} + 4 x + (- 3 x - 3 \cdot - 7) (1 + 4 \frac{1}{x}) x}{x^{3}}$

Step 3.8.3.1.2.1.2

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

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Step 3.8.3.1.2.1.2.1

Move $x$ .

$\frac{2 (x \cdot x) + x \cdot 4 - 7 (2 x) - 7 \cdot 4 + x^{2} + 4 x + (- 3 x - 3 \cdot - 7) (1 + 4 \frac{1}{x}) x}{x^{3}}$

Step 3.8.3.1.2.1.2.2

Multiply $x$ by $x$ .

$\frac{2 x^{2} + x \cdot 4 - 7 (2 x) - 7 \cdot 4 + x^{2} + 4 x + (- 3 x - 3 \cdot - 7) (1 + 4 \frac{1}{x}) x}{x^{3}}$

Step 3.8.3.1.2.1.3

Move $4$ to the left of $x$ .

$\frac{2 x^{2} + 4 \cdot x - 7 (2 x) - 7 \cdot 4 + x^{2} + 4 x + (- 3 x - 3 \cdot - 7) (1 + 4 \frac{1}{x}) x}{x^{3}}$

Step 3.8.3.1.2.1.4

Multiply $2$ by $- 7$ .

$\frac{2 x^{2} + 4 x - 14 x - 7 \cdot 4 + x^{2} + 4 x + (- 3 x - 3 \cdot - 7) (1 + 4 \frac{1}{x}) x}{x^{3}}$

Step 3.8.3.1.2.1.5

Multiply $- 7$ by $4$ .

$\frac{2 x^{2} + 4 x - 14 x - 28 + x^{2} + 4 x + (- 3 x - 3 \cdot - 7) (1 + 4 \frac{1}{x}) x}{x^{3}}$

Step 3.8.3.1.2.2

Subtract $14 x$ from $4 x$ .

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x + (- 3 x - 3 \cdot - 7) (1 + 4 \frac{1}{x}) x}{x^{3}}$

Step 3.8.3.1.3

Multiply $- 3$ by $- 7$ .

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x + (- 3 x + 21) (1 + 4 \frac{1}{x}) x}{x^{3}}$

Step 3.8.3.1.4

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

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x + (- 3 x + 21) (1 + \frac{4}{x}) x}{x^{3}}$

Step 3.8.3.1.5

Expand $(- 3 x + 21) (1 + \frac{4}{x})$ using the FOIL Method.

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Step 3.8.3.1.5.1

Apply the distributive property.

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x + (- 3 x (1 + \frac{4}{x}) + 21 (1 + \frac{4}{x})) x}{x^{3}}$

Step 3.8.3.1.5.2

Apply the distributive property.

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x + (- 3 x \cdot 1 - 3 x \frac{4}{x} + 21 (1 + \frac{4}{x})) x}{x^{3}}$

Step 3.8.3.1.5.3

Apply the distributive property.

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x + (- 3 x \cdot 1 - 3 x \frac{4}{x} + 21 \cdot 1 + 21 \frac{4}{x}) x}{x^{3}}$

Step 3.8.3.1.6

Simplify and combine like terms.

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Step 3.8.3.1.6.1

Simplify each term.

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Step 3.8.3.1.6.1.1

Multiply $- 3$ by $1$ .

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x + (- 3 x - 3 x \frac{4}{x} + 21 \cdot 1 + 21 \frac{4}{x}) x}{x^{3}}$

Step 3.8.3.1.6.1.2

Cancel the common factor of $x$ .

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Step 3.8.3.1.6.1.2.1

Factor $x$ out of $- 3 x$ .

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x + (- 3 x + x \cdot - 3 \frac{4}{x} + 21 \cdot 1 + 21 \frac{4}{x}) x}{x^{3}}$

Step 3.8.3.1.6.1.2.2

Cancel the common factor.

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x + (- 3 x + x \cdot - 3 \frac{4}{x} + 21 \cdot 1 + 21 \frac{4}{x}) x}{x^{3}}$

Step 3.8.3.1.6.1.2.3

Rewrite the expression.

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x + (- 3 x - 3 \cdot 4 + 21 \cdot 1 + 21 \frac{4}{x}) x}{x^{3}}$

Step 3.8.3.1.6.1.3

Multiply $- 3$ by $4$ .

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x + (- 3 x - 12 + 21 \cdot 1 + 21 \frac{4}{x}) x}{x^{3}}$

Step 3.8.3.1.6.1.4

Multiply $21$ by $1$ .

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x + (- 3 x - 12 + 21 + 21 \frac{4}{x}) x}{x^{3}}$

Step 3.8.3.1.6.1.5

Multiply $21 \frac{4}{x}$ .

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Step 3.8.3.1.6.1.5.1

Combine $21$ and $\frac{4}{x}$ .

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x + (- 3 x - 12 + 21 + \frac{21 \cdot 4}{x}) x}{x^{3}}$

Step 3.8.3.1.6.1.5.2

Multiply $21$ by $4$ .

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x + (- 3 x - 12 + 21 + \frac{84}{x}) x}{x^{3}}$

Step 3.8.3.1.6.2

Add $- 12$ and $21$ .

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x + (- 3 x + 9 + \frac{84}{x}) x}{x^{3}}$

Step 3.8.3.1.7

Apply the distributive property.

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x - 3 x \cdot x + 9 x + \frac{84}{x} x}{x^{3}}$

Step 3.8.3.1.8

Simplify.

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Step 3.8.3.1.8.1

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

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Step 3.8.3.1.8.1.1

Move $x$ .

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x - 3 (x \cdot x) + 9 x + \frac{84}{x} x}{x^{3}}$

Step 3.8.3.1.8.1.2

Multiply $x$ by $x$ .

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x - 3 x^{2} + 9 x + \frac{84}{x} x}{x^{3}}$

Step 3.8.3.1.8.2

Cancel the common factor of $x$ .

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Step 3.8.3.1.8.2.1

Cancel the common factor.

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x - 3 x^{2} + 9 x + \frac{84}{x} x}{x^{3}}$

Step 3.8.3.1.8.2.2

Rewrite the expression.

$\frac{2 x^{2} - 10 x - 28 + x^{2} + 4 x - 3 x^{2} + 9 x + 84}{x^{3}}$

Step 3.8.3.2

Add $2 x^{2}$ and $x^{2}$ .

$\frac{3 x^{2} - 10 x - 28 + 4 x - 3 x^{2} + 9 x + 84}{x^{3}}$

Step 3.8.3.3

Combine the opposite terms in $3 x^{2} - 10 x - 28 + 4 x - 3 x^{2} + 9 x + 84$ .

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Step 3.8.3.3.1

Subtract $3 x^{2}$ from $3 x^{2}$ .

$\frac{- 10 x - 28 + 4 x + 0 + 9 x + 84}{x^{3}}$

Step 3.8.3.3.2

Add $- 10 x - 28 + 4 x$ and $0$ .

$\frac{- 10 x - 28 + 4 x + 9 x + 84}{x^{3}}$

Step 3.8.3.4

Add $- 10 x$ and $4 x$ .

$\frac{- 6 x - 28 + 9 x + 84}{x^{3}}$

Step 3.8.3.5

Add $- 6 x$ and $9 x$ .

$\frac{3 x - 28 + 84}{x^{3}}$

Step 3.8.3.6

Add $- 28$ and $84$ .

$\frac{3 x + 56}{x^{3}}$

Step 4

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

$y' = \frac{3 x + 56}{x^{3}}$

Step 5

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

$\frac{d y}{d x} = \frac{3 x + 56}{x^{3}}$