Answer
$3\sqrt{3}$
Work Step by Step
RECALL:
For any non-negative real numbers $a$ and $b$,
$\sqrt{ab} = \sqrt{a}\cdot \sqrt{b}$ and $\sqrt{a} \cdot \sqrt{b} = \sqrt{ab}$.
Simplify the given expression by using the rule above to obtain
$\sqrt{9} \cdot \sqrt{3}
\\=\sqrt{3^2} \cdot \sqrt{3}
\\=3\sqrt{3}.$
