Answer
$-2\sqrt 6$
Work Step by Step
Recall that the definition $\sqrt{-a} = i\sqrt{a}$ must be applied BEFORE the other rules regarding radicals, therefore,
$\sqrt{-3}*\sqrt{-8} =i\sqrt{3}*i\sqrt{8} $
$i^2\sqrt{24}$
$(-1)(2\sqrt 6)$
$$-2\sqrt 6$$
