Calculus Examples

$y = \frac{5 - 7 x + 9 x^{2}}{x^{2}}$

Step 1

Differentiate both sides of the equation.

$\frac{d}{d x} (y) = \frac{d}{d x} (\frac{5 - 7 x + 9 x^{2}}{x^{2}})$

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 $f (x) = 5 - 7 x + 9 x^{2}$ and $g (x) = x^{2}$ .

$\frac{x^{2} \frac{d}{d x} [5 - 7 x + 9 x^{2}] - (5 - 7 x + 9 x^{2}) \frac{d}{d x} [x^{2}]}{{(x^{2})}^{2}}$

Step 3.2

Differentiate.

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Step 3.2.1

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

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Step 3.2.1.1

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

$\frac{x^{2} \frac{d}{d x} [5 - 7 x + 9 x^{2}] - (5 - 7 x + 9 x^{2}) \frac{d}{d x} [x^{2}]}{x^{2 \cdot 2}}$

Step 3.2.1.2

Multiply $2$ by $2$ .

$\frac{x^{2} \frac{d}{d x} [5 - 7 x + 9 x^{2}] - (5 - 7 x + 9 x^{2}) \frac{d}{d x} [x^{2}]}{x^{4}}$

Step 3.2.2

By the Sum Rule, the derivative of $5 - 7 x + 9 x^{2}$ with respect to $x$ is $\frac{d}{d x} [5] + \frac{d}{d x} [- 7 x] + \frac{d}{d x} [9 x^{2}]$ .

$\frac{x^{2} (\frac{d}{d x} [5] + \frac{d}{d x} [- 7 x] + \frac{d}{d x} [9 x^{2}]) - (5 - 7 x + 9 x^{2}) \frac{d}{d x} [x^{2}]}{x^{4}}$

Step 3.2.3

Since $5$ is constant with respect to $x$ , the derivative of $5$ with respect to $x$ is $0$ .

$\frac{x^{2} (0 + \frac{d}{d x} [- 7 x] + \frac{d}{d x} [9 x^{2}]) - (5 - 7 x + 9 x^{2}) \frac{d}{d x} [x^{2}]}{x^{4}}$

Step 3.2.4

Add $0$ and $\frac{d}{d x} [- 7 x]$ .

$\frac{x^{2} (\frac{d}{d x} [- 7 x] + \frac{d}{d x} [9 x^{2}]) - (5 - 7 x + 9 x^{2}) \frac{d}{d x} [x^{2}]}{x^{4}}$

Step 3.2.5

Since $- 7$ is constant with respect to $x$ , the derivative of $- 7 x$ with respect to $x$ is $- 7 \frac{d}{d x} [x]$ .

$\frac{x^{2} (- 7 \frac{d}{d x} [x] + \frac{d}{d x} [9 x^{2}]) - (5 - 7 x + 9 x^{2}) \frac{d}{d x} [x^{2}]}{x^{4}}$

Step 3.2.6

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

$\frac{x^{2} (- 7 \cdot 1 + \frac{d}{d x} [9 x^{2}]) - (5 - 7 x + 9 x^{2}) \frac{d}{d x} [x^{2}]}{x^{4}}$

Step 3.2.7

Multiply $- 7$ by $1$ .

$\frac{x^{2} (- 7 + \frac{d}{d x} [9 x^{2}]) - (5 - 7 x + 9 x^{2}) \frac{d}{d x} [x^{2}]}{x^{4}}$

Step 3.2.8

Since $9$ is constant with respect to $x$ , the derivative of $9 x^{2}$ with respect to $x$ is $9 \frac{d}{d x} [x^{2}]$ .

$\frac{x^{2} (- 7 + 9 \frac{d}{d x} [x^{2}]) - (5 - 7 x + 9 x^{2}) \frac{d}{d x} [x^{2}]}{x^{4}}$

Step 3.2.9

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

$\frac{x^{2} (- 7 + 9 (2 x)) - (5 - 7 x + 9 x^{2}) \frac{d}{d x} [x^{2}]}{x^{4}}$

Step 3.2.10

Multiply $2$ by $9$ .

$\frac{x^{2} (- 7 + 18 x) - (5 - 7 x + 9 x^{2}) \frac{d}{d x} [x^{2}]}{x^{4}}$

Step 3.2.11

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

$\frac{x^{2} (- 7 + 18 x) - (5 - 7 x + 9 x^{2}) (2 x)}{x^{4}}$

Step 3.2.12

Simplify with factoring out.

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Step 3.2.12.1

Multiply $2$ by $- 1$ .

$\frac{x^{2} (- 7 + 18 x) - 2 (5 - 7 x + 9 x^{2}) x}{x^{4}}$

Step 3.2.12.2

Factor $x$ out of $x^{2} (- 7 + 18 x) - 2 (5 - 7 x + 9 x^{2}) x$ .

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Step 3.2.12.2.1

Factor $x$ out of $x^{2} (- 7 + 18 x)$ .

$\frac{x (x (- 7 + 18 x)) - 2 (5 - 7 x + 9 x^{2}) x}{x^{4}}$

Step 3.2.12.2.2

Factor $x$ out of $- 2 (5 - 7 x + 9 x^{2}) x$ .

$\frac{x (x (- 7 + 18 x)) + x (- 2 (5 - 7 x + 9 x^{2}))}{x^{4}}$

Step 3.2.12.2.3

Factor $x$ out of $x (x (- 7 + 18 x)) + x (- 2 (5 - 7 x + 9 x^{2}))$ .

$\frac{x (x (- 7 + 18 x) - 2 (5 - 7 x + 9 x^{2}))}{x^{4}}$

Step 3.3

Cancel the common factors.

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Step 3.3.1

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

$\frac{x (x (- 7 + 18 x) - 2 (5 - 7 x + 9 x^{2}))}{x \cdot x^{3}}$

Step 3.3.2

Cancel the common factor.

$\frac{x (x (- 7 + 18 x) - 2 (5 - 7 x + 9 x^{2}))}{x \cdot x^{3}}$

Step 3.3.3

Rewrite the expression.

$\frac{x (- 7 + 18 x) - 2 (5 - 7 x + 9 x^{2})}{x^{3}}$

Step 3.4

Simplify.

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Step 3.4.1

Apply the distributive property.

$\frac{x \cdot - 7 + x (18 x) - 2 (5 - 7 x + 9 x^{2})}{x^{3}}$

Step 3.4.2

Apply the distributive property.

$\frac{x \cdot - 7 + x (18 x) - 2 \cdot 5 - 2 (- 7 x) - 2 (9 x^{2})}{x^{3}}$

Step 3.4.3

Simplify the numerator.

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Step 3.4.3.1

Simplify each term.

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Step 3.4.3.1.1

Move $- 7$ to the left of $x$ .

$\frac{- 7 \cdot x + x (18 x) - 2 \cdot 5 - 2 (- 7 x) - 2 (9 x^{2})}{x^{3}}$

Step 3.4.3.1.2

Rewrite using the commutative property of multiplication.

$\frac{- 7 x + 18 x \cdot x - 2 \cdot 5 - 2 (- 7 x) - 2 (9 x^{2})}{x^{3}}$

Step 3.4.3.1.3

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

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Step 3.4.3.1.3.1

Move $x$ .

$\frac{- 7 x + 18 (x \cdot x) - 2 \cdot 5 - 2 (- 7 x) - 2 (9 x^{2})}{x^{3}}$

Step 3.4.3.1.3.2

Multiply $x$ by $x$ .

$\frac{- 7 x + 18 x^{2} - 2 \cdot 5 - 2 (- 7 x) - 2 (9 x^{2})}{x^{3}}$

Step 3.4.3.1.4

Multiply $- 2$ by $5$ .

$\frac{- 7 x + 18 x^{2} - 10 - 2 (- 7 x) - 2 (9 x^{2})}{x^{3}}$

Step 3.4.3.1.5

Multiply $- 7$ by $- 2$ .

$\frac{- 7 x + 18 x^{2} - 10 + 14 x - 2 (9 x^{2})}{x^{3}}$

Step 3.4.3.1.6

Multiply $9$ by $- 2$ .

$\frac{- 7 x + 18 x^{2} - 10 + 14 x - 18 x^{2}}{x^{3}}$

Step 3.4.3.2

Combine the opposite terms in $- 7 x + 18 x^{2} - 10 + 14 x - 18 x^{2}$ .

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Step 3.4.3.2.1

Subtract $18 x^{2}$ from $18 x^{2}$ .

$\frac{- 7 x - 10 + 14 x + 0}{x^{3}}$

Step 3.4.3.2.2

Add $- 7 x - 10 + 14 x$ and $0$ .

$\frac{- 7 x - 10 + 14 x}{x^{3}}$

Step 3.4.3.3

Add $- 7 x$ and $14 x$ .

$\frac{7 x - 10}{x^{3}}$

Step 4

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

$y' = \frac{7 x - 10}{x^{3}}$

Step 5

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

$\frac{d y}{d x} = \frac{7 x - 10}{x^{3}}$