Answer
$10$
Work Step by Step
Using the properties of radicals, the given expression, $
2\sqrt{5}\cdot\sqrt{5}
,$ simplifies to
\begin{array}{l}\require{cancel}
2\sqrt{5}\cdot1\sqrt{5}
\\\\=
2(1)\sqrt{5(5)}
\\\\=
2\sqrt{(5)^2}
\\\\=
2(5)
\\\\=
10
.\end{array}
