# How do you find f(-4) when f(x)=8x+11?

Mar 4, 2017

See the entire solution process below:

#### Explanation:

To find $f \left(- 4\right)$, substitute $\textcolor{red}{- 4}$ for every occurrence of $\textcolor{red}{x}$ in the function $f \left(x\right)$:

$f \left(\textcolor{red}{x}\right) = 8 \textcolor{red}{x} + 11$ becomes:

$f \left(\textcolor{red}{- 4}\right) = \left(8 \times \textcolor{red}{- 4}\right) + 11$

$f \left(\textcolor{red}{- 4}\right) = - 32 + 11$

$f \left(\textcolor{red}{- 4}\right) = - 21$