Answer
$20+i\sqrt{5}$
Work Step by Step
Factor the radicand so that one factor $-1$ to obtain:
$=20+\sqrt{5(-1)}$
RECALL:
(1) $\sqrt{ab} = \sqrt{a} \cdot \sqrt{b}$
(2) $\sqrt{-1} = i$
Use rule (1) above to obtain:
$=20+ \sqrt{5} \cdot \sqrt{-1}$
Use rule (2) above to obtain:
$=20+\sqrt{5} \cdot i
\\=20+i\sqrt{5}$
