Question 421903
Apply the difference of two squares, rewriting {{{x^4}}} as {{{(x^2)^2}}} to obtain


{{{(x^2 - 9)(x^2 + 9)}}} We can apply the formula again to obtain


{{{(x+3)(x-3)(x^2 + 9)}}}


{{{x^2 + 9}}} cannot be factored over the real numbers, so we leave it in this form.