Answer
$5\sqrt{2}$
Work Step by Step
Using the properties of radicals, the given expression, $
\sqrt{5}\sqrt{10}
,$ simplifies to
\begin{array}{l}\require{cancel}
\sqrt{5(10)}
\\\\=
\sqrt{50}
\\\\=
\sqrt{25\cdot2}
\\\\=
\sqrt{(5)^2\cdot2}
\\\\=
5\sqrt{2}
\end{array}