Answer
$36x^{2}$
Work Step by Step
Using $(x^ay^b)^c=x^{ac}y^{bc}$ or the products-to-powers rule, the given expression, $
(-6x)^2
,$ simplifies to
\begin{array}{l}\require{cancel}
(-6)^{1(2)}x^{1(2)}
\\\\=
(-6)^{2}x^{2}
\\\\=
36x^{2}
.\end{array}