Answer
$5y^4(2+3y^2)$
Work Step by Step
Factoring the $GCF=
5y^4
,$ the given expression, $
10y^4+15y^6
,$ is equivalent to
\begin{array}{l}\require{cancel}
5y^4
\left(
\dfrac{10y^4}{5y^4}+\dfrac{15y^6}{5y^4}
\right)
\\\\=
5y^4(2+3y^2)
.\end{array}