#### Answer

$x=-4,0,4$

#### Work Step by Step

First, set the terms in the parentheses equal to zero, and do the same with $3x^{2}$. Then solve for each and include each solution in the final answer.
$3x^{2}(x^{2}-16)=0$
$x^{2}-16=0$
$x=±4$
$3x^{2}=0$
$x=0$
$x=-4,0,4$