Answer
$2 \sqrt{2}$
Work Step by Step
Factor the radicand so that one fo the factors is a perfect square number.
$\sqrt8=\sqrt{4\cdot 2}$
Use $4=2^2$.
$=\sqrt{2^2\cdot 2}$
Separate square root using the rule $\sqrt{ab}=\sqrt{a}\cdot \sqrt{b}$.
$=\sqrt{2^2}\cdot \sqrt{2}$
Simplify.
$=2 \sqrt{2}$
Hence, the correct answer is $2 \sqrt{2}$.
