Answer
{$-8,-6,4,6$}
Work Step by Step
Since, $|x^2+2x-36|=12$
Apply the definition of Absolute value.
We have $x^2+2x-36=12$ and $x^2+2x-36=-12$
This implies that $x^2+2x-48=0$ and $x^2+2x-24=0$
$(x+8)(x-6)=0$ and $(x+6)(x-4)=0$
Thus, $x=-8,6$ and $x=-6,4$
Solution set is $x=${$-8,-6,4,6$}