Answer
$m\approx -0.71$ and $m\approx-11.29$.
Work Step by Step
The given equation is
$\Rightarrow m^2+12m=-8$
Find the value of $(\frac{b}{2})^2$.
Substitute $12$ for $b$.
$=(\frac{12}{2})^2$
Simplify.
$=(6)^2$
$=36$
Add $36$ to each side of the euqation.
$\Rightarrow m^2+12m+36=-8+36$
Simplify.
$\Rightarrow m^2+12m+36=28$
Write the left side as the square of a binomial.
$\Rightarrow (m+6)^2=28$
Take the square root of each side.
$\Rightarrow m+6=\pm \sqrt{28}$
Subtract $6$ from each side.
$\Rightarrow m+6-6=\pm \sqrt{28}-6$
Simplify.
$\Rightarrow m=\pm \sqrt{28}-6$
The solutions are $m= \sqrt{28}-6\approx -0.71$ and $m=- \sqrt{28}-6\approx-11.29$.
