Answer
$10i\sqrt5$
Work Step by Step
Factor the radicand so that one factor is a perfect square then simplify to obtain:
$=\sqrt{100(-5)}
\\=\sqrt{10^2(-5)}
\\=10\sqrt{-5}$
Factor out $-1$ in the radicand to obtain:
$=10\sqrt{-1(5)}$
Since $\sqrt{-1} = i$, bring out the square root of $-1$, which is $i$, to obtain:
$=10i\sqrt5$
