Answer
$3x^2(3x^2+6+2)$
Work Step by Step
Factoring the $GCF=
3x^2
,$ the given expression, $
9x^4+18x^3+6x^2
,$ is equivalent to
\begin{array}{l}\require{cancel}
3x^2
\left(
\dfrac{9x^4}{3x^2}+\dfrac{18x^3}{3x^2}+\dfrac{6x^2}{3x^2}
\right)
\\\\=
3x^2(3x^2+6+2)
.\end{array}