Answer
$3x^2(2x+5)$
Work Step by Step
Factoring the $GCF=
3x^2
,$ the given expression, $
6x^3+15x^2
,$ is equivalent to
\begin{array}{l}\require{cancel}
3x^2
\left(
\dfrac{6x^3}{3x^2}+\dfrac{15x^2}{3x^2}
\right)
\\\\=
3x^2(2x+5)
.\end{array}