Answer
$2\sqrt[4]{2}$
Work Step by Step
RECALL:
For any non-negative real numbers a and b,
$\sqrt[n]{a} \cdot \sqrt[n]{b} = \sqrt[n]{ab}$
Use the rule above to obtain:
$=\sqrt[4]{(4)(8)}
\\=\sqrt[4]{32}$
Factor the radicand (expression inside the radical sign) so that at least one factor is a perfect fourth root, and then simplify to obtain:
$\\=\sqrt[4]{16(2)}
\\=\sqrt[4]{2^4(2)}
\\=2\sqrt[4]{2}$
