Precalculus Examples

$F (x) = - 3 x^{2} + 2$

Step 1

Consider the difference quotient formula.

$\frac{f (x + h) - f (x)}{h}$

Step 2

Find the components of the definition.

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Step 2.1

Evaluate the function at $x = x + h$ .

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Step 2.1.1

Replace the variable $x$ with $x + h$ in the expression.

$F (x + h) = - 3 {(x + h)}^{2} + 2$

Step 2.1.2

Simplify the result.

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Step 2.1.2.1

Simplify each term.

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Step 2.1.2.1.1

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

$F (x + h) = - 3 ((x + h) (x + h)) + 2$

Step 2.1.2.1.2

Expand $(x + h) (x + h)$ using the FOIL Method.

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Step 2.1.2.1.2.1

Apply the distributive property.

$F (x + h) = - 3 (x (x + h) + h (x + h)) + 2$

Step 2.1.2.1.2.2

Apply the distributive property.

$F (x + h) = - 3 (x \cdot x + x h + h (x + h)) + 2$

Step 2.1.2.1.2.3

Apply the distributive property.

$F (x + h) = - 3 (x \cdot x + x h + h x + h \cdot h) + 2$

Step 2.1.2.1.3

Simplify and combine like terms.

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Step 2.1.2.1.3.1

Simplify each term.

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Step 2.1.2.1.3.1.1

Multiply $x$ by $x$ .

$F (x + h) = - 3 (x^{2} + x h + h x + h \cdot h) + 2$

Step 2.1.2.1.3.1.2

Multiply $h$ by $h$ .

$F (x + h) = - 3 (x^{2} + x h + h x + h^{2}) + 2$

Step 2.1.2.1.3.2

Add $x h$ and $h x$ .

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Step 2.1.2.1.3.2.1

Reorder $x$ and $h$ .

$F (x + h) = - 3 (x^{2} + h x + h x + h^{2}) + 2$

Step 2.1.2.1.3.2.2

Add $h x$ and $h x$ .

$F (x + h) = - 3 (x^{2} + 2 h x + h^{2}) + 2$

Step 2.1.2.1.4

Apply the distributive property.

$F (x + h) = - 3 x^{2} - 3 (2 h x) - 3 h^{2} + 2$

Step 2.1.2.1.5

Multiply $2$ by $- 3$ .

$F (x + h) = - 3 x^{2} - 6 h x - 3 h^{2} + 2$

Step 2.1.2.2

The final answer is $- 3 x^{2} - 6 h x - 3 h^{2} + 2$ .

$- 3 x^{2} - 6 h x - 3 h^{2} + 2$

Step 2.2

Reorder.

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Step 2.2.1

Move $- 3 x^{2}$ .

$- 6 h x - 3 h^{2} - 3 x^{2} + 2$

Step 2.2.2

Reorder $- 6 h x$ and $- 3 h^{2}$ .

$- 3 h^{2} - 6 h x - 3 x^{2} + 2$

Step 2.3

Find the components of the definition.

$F (x + h) = - 3 h^{2} - 6 h x - 3 x^{2} + 2$

$F (x) = - 3 x^{2} + 2$

$F (x + h) = - 3 h^{2} - 6 h x - 3 x^{2} + 2$

$F (x) = - 3 x^{2} + 2$

Step 3

Plug in the components.

$\frac{F (x + h) - F x}{h} = \frac{- 3 h^{2} - 6 h x - 3 x^{2} + 2 - (- 3 x^{2} + 2)}{h}$

Step 4

Simplify.

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Step 4.1

Simplify the numerator.

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Step 4.1.1

Apply the distributive property.

$\frac{- 3 h^{2} - 6 h x - 3 x^{2} + 2 - (- 3 x^{2}) - 1 \cdot 2}{h}$

Step 4.1.2

Multiply $- 3$ by $- 1$ .

$\frac{- 3 h^{2} - 6 h x - 3 x^{2} + 2 + 3 x^{2} - 1 \cdot 2}{h}$

Step 4.1.3

Multiply $- 1$ by $2$ .

$\frac{- 3 h^{2} - 6 h x - 3 x^{2} + 2 + 3 x^{2} - 2}{h}$

Step 4.1.4

Add $- 3 x^{2}$ and $3 x^{2}$ .

$\frac{- 3 h^{2} - 6 h x + 0 + 2 - 2}{h}$

Step 4.1.5

Add $- 3 h^{2}$ and $0$ .

$\frac{- 3 h^{2} - 6 h x + 2 - 2}{h}$

Step 4.1.6

Subtract $2$ from $2$ .

$\frac{- 3 h^{2} - 6 h x + 0}{h}$

Step 4.1.7

Add $- 3 h^{2} - 6 h x$ and $0$ .

$\frac{- 3 h^{2} - 6 h x}{h}$

Step 4.1.8

Factor $3 h$ out of $- 3 h^{2} - 6 h x$ .

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Step 4.1.8.1

Factor $3 h$ out of $- 3 h^{2}$ .

$\frac{3 h (- h) - 6 h x}{h}$

Step 4.1.8.2

Factor $3 h$ out of $- 6 h x$ .

$\frac{3 h (- h) + 3 h (- 2 x)}{h}$

Step 4.1.8.3

Factor $3 h$ out of $3 h (- h) + 3 h (- 2 x)$ .

$\frac{3 h (- h - 2 x)}{h}$

Step 4.2

Simplify terms.

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Step 4.2.1

Cancel the common factor of $h$ .

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Step 4.2.1.1

Cancel the common factor.

$\frac{3 h (- h - 2 x)}{h}$

Step 4.2.1.2

Divide $3 (- h - 2 x)$ by $1$ .

$3 (- h - 2 x)$

Step 4.2.2

Apply the distributive property.

$3 (- h) + 3 (- 2 x)$

Step 4.2.3

Simplify the expression.

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Step 4.2.3.1

Multiply $- 1$ by $3$ .

$- 3 h + 3 (- 2 x)$

Step 4.2.3.2

Multiply $- 2$ by $3$ .

$- 3 h - 6 x$

Step 4.2.3.3

Reorder $- 3 h$ and $- 6 x$ .

$- 6 x - 3 h$

Step 5