Answer
$-3\sqrt{5}$
Work Step by Step
RECALL:
(1) $\sqrt{-1}=i$
(2) $i^2=-1$
(3) $\sqrt{ab} = \sqrt{a} \cdot \sqrt{b}$
Simplify each radical by using rules (1) and (3) above:
$=\sqrt{9(-1)} \cdot \sqrt{5(-1)}
\\=\sqrt{3^2(-1)} \cdot (\sqrt{5} \cdot \sqrt{-1})
\\=3\sqrt{-1} \cdot (\sqrt{5} \cdot i)
\\=3i \cdot i\sqrt{5}
\\=3i^2\sqrt{5}$
Use rule (2) above to obtain:
$=3(-1)\sqrt{5}
\\=-3\sqrt{5}$
