Precalculus Examples

$f (x) = - x^{2} + 6 x + 4$ Find $f (- 7)$

Step 1

Replace the variable $x$ with $- 7$ in the expression.

$f (- 7) = - {(- 7)}^{2} + 6 (- 7) + 4$

Step 2

Simplify $- {(- 7)}^{2} + 6 (- 7) + 4$ .

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Step 2.1

Remove parentheses.

$- {(- 7)}^{2} + 6 (- 7) + 4$

Step 2.2

Simplify each term.

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Step 2.2.1

Raise $- 7$ to the power of $2$ .

$- 1 \cdot 49 + 6 (- 7) + 4$

Step 2.2.2

Multiply $- 1$ by $49$ .

$- 49 + 6 (- 7) + 4$

Step 2.2.3

Multiply $6$ by $- 7$ .

$- 49 - 42 + 4$

Step 2.3

Simplify by adding and subtracting.

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Step 2.3.1

Subtract $42$ from $- 49$ .

$- 91 + 4$

Step 2.3.2

Add $- 91$ and $4$ .

$- 87$