Answer
$x=\{-6,2\}$
Work Step by Step
Using the completing the square method, the solutions of the given quadratic equation, $
x^2+4x=12
,$ is
\begin{array}{l}\require{cancel}
x^2+4x+\left( \dfrac{4}{2} \right)^2=12+\left( \dfrac{4}{2} \right)^2
\\\\
x^2+4x+4=12+4
\\\\
(x+2)^2=16
\\\\
x+2=\pm\sqrt{16}
\\\\
x+2=\pm4
\\\\
x=-2\pm4
\\\\
x=\{-6,2\}
.\end{array}
