Question

PLSSSSSS I NEED HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Simplify the Expression:

$\sqrt{9a^{2} }$, if a<0

Answer 1

$\sqrt{9a^{2}}=\sqrt{9}\sqrt{a^{2}}=3|a|$

As $a < 0$, $|a|=-a$, so $3|a|=\boxed{-3a}$