#### Answer

$5y^2\sqrt{3y}$

#### Work Step by Step

Using the properties of radicals, the given expression, $
\sqrt{75y^5}
,$ simplifies to
\begin{array}{l}\require{cancel}
\sqrt{25y^4\cdot3y}
\\\\=
\sqrt{(5y^2)^2\cdot3y}
.\\\\=
5y^2\sqrt{3y}
\end{array}
* Note that it is assumed that no radicands were formed by raising negative numbers to even powers.