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 binomial 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:
$=(x^2-1)(x^2+1)$
Factor the first binomial (a difference of two squares) using the formula above with $a=x$ and $b=1$ to obtain:
$=(x-1)(x+1)(x^2+1)$
