Answer
$-32y^4\sqrt{5y}$
Work Step by Step
Using the properties of radicals, the given expression, $
-8\sqrt{80y^9}
,$ simplifies to
\begin{array}{l}\require{cancel}
-8\sqrt{16y^8\cdot5y}
\\\\=
-8\sqrt{(4y^4)^2\cdot5y}
\\\\=
-8\cdot4y^4\sqrt{5y}
\\\\=
-32y^4\sqrt{5y}
.\end{array}
Note that all of the variables are assumed to represent non-negative real numbers.
