Precalculus Examples

$f (x) = - x^{2} - 10 x$ Find $f (- 5)$

Step 1

Replace the variable $x$ with $- 5$ in the expression.

$f (- 5) = - {(- 5)}^{2} - 10 \cdot - 5$

Step 2

Simplify $- {(- 5)}^{2} - 10 \cdot - 5$ .

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Step 2.1

Remove parentheses.

$- {(- 5)}^{2} - 10 \cdot - 5$

Step 2.2

Simplify each term.

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Step 2.2.1

Raise $- 5$ to the power of $2$ .

$- 1 \cdot 25 - 10 \cdot - 5$

Step 2.2.2

Multiply $- 1$ by $25$ .

$- 25 - 10 \cdot - 5$

Step 2.2.3

Multiply $- 10$ by $- 5$ .

$- 25 + 50$

Step 2.3

Add $- 25$ and $50$ .

$25$