Answer
$\sqrt[5]{80y^4}$
Work Step by Step
Using $\sqrt[a]{x}\sqrt[a]{y}=\sqrt[a]{xy}$, the given expression, $
\sqrt[5]{8y^3}\sqrt[5]{10y}
,$ simplifies to
\begin{array}{l}\require{cancel}
\sqrt[5]{8y^3(10y)}
\\\\=
\sqrt[5]{80y^4}
.\end{array}