# How do you solve (x + 8)^2 = 81?

Feb 27, 2016

$x = 1 \mathmr{and} x = - 17$

#### Explanation:

${\left(x + 8\right)}^{2} = 81 = {\left(\pm 9\right)}^{2}$

$\Rightarrow \left(x + 8\right) = \pm 9$

If $\left(x + 8\right) = + 9$ then
$\textcolor{w h i t e}{\text{XXX}} x = + 9 - 8 = 7$

If $\left(x + 8\right) = - 9$ then
$\textcolor{w h i t e}{\text{XXX}} x = - 9 - 8 = - 17$