Precalculus Examples

$f (x) = - 2 x^{2} - 4 x - 18$ Find $f (- 6)$

Step 1

Replace the variable $x$ with $- 6$ in the expression.

$f (- 6) = - 2 {(- 6)}^{2} - 4 \cdot - 6 - 18$

Step 2

Simplify $- 2 {(- 6)}^{2} - 4 \cdot - 6 - 18$ .

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Step 2.1

Remove parentheses.

$- 2 {(- 6)}^{2} - 4 \cdot - 6 - 18$

Step 2.2

Simplify each term.

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Step 2.2.1

Raise $- 6$ to the power of $2$ .

$- 2 \cdot 36 - 4 \cdot - 6 - 18$

Step 2.2.2

Multiply $- 2$ by $36$ .

$- 72 - 4 \cdot - 6 - 18$

Step 2.2.3

Multiply $- 4$ by $- 6$ .

$- 72 + 24 - 18$

Step 2.3

Simplify by adding and subtracting.

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Step 2.3.1

Add $- 72$ and $24$ .

$- 48 - 18$

Step 2.3.2

Subtract $18$ from $- 48$ .

$- 66$