Answer
$-8$
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 rule (1) above:
$=\sqrt{16(-1)} \cdot \sqrt{4(-1)}
\\=\sqrt{4^2(-1)} \cdot \sqrt{2^2(-1)}
\\=4\sqrt{-1} \cdot 2\sqrt{-1}
\\=4i \cdot 2i
\\=8i^2$
Use rule (2) above to obtain:
$=8(-1)
\\=-8$
