Answer
$-6(2x^2-3)$
Work Step by Step
Factoring the negative $GCF=
-6
,$ the given expression, $
-12x^2+18
,$ is equivalent to
\begin{array}{l}\require{cancel}
-6
\left(
\dfrac{-12x^2}{-6}+\dfrac{18}{-6}
\right)
\\\\=
-6(2x^2-3)
.\end{array}