Answer
$2(x^{2}+9)(x-3)(x+3)$
Work Step by Step
$ 2x^{4}-162\qquad$...factor out the GCF, $2$.
$=2(x^{4}-81)\qquad$...recognize the difference of two squares: $a^{2}-b^{2}=(a-b)(a+b)$
$=2(x^{2}-9)(x^{2}+9)\qquad$...once again, recognize the difference of two squares: $a^{2}-b^{2}=(a-b)(a+b)$
$=2(x^{2}+9)(x-3)(x+3)$
