# How do you simplify sqrt 20?

$\sqrt{20} = 2 \sqrt{5}$
$\sqrt{20} = \sqrt{4 \cdot 5} = \sqrt{{2}^{2} \cdot 5} = \sqrt{{2}^{2}} \cdot \sqrt{5} = 2 \sqrt{5}$
If $a , b \ge 0$ then $\sqrt{a b} = \sqrt{a} \sqrt{b}$