Answer
$(x-1)(x+1)(x^2+1)$
Work Step by Step
The given expression can be written as
$(x^2)^2-1^2.$
The expression above is a difference of two squares.
RECALL:
$a^2-b^2=(a-b)(a+b).$
Factor the difference of two squares using the formula above with $a=x^2$ and $b=1$ to obtain
$(x^2-1)(x^2+1)
\\=(x^2-1^2)(x^2+1).$
Factor the difference of two squares with $a=x$ and $b=1$ to obtain
$(x-1)(x+1)(x^2+1).$
