Factor x4−1x^4 - 1x4−1 completely over the reals.
(x2−1)2(x^2 - 1)^2(x2−1)2
(x−1)(x+1)(x2+1)(x - 1)(x + 1)(x^2 + 1)(x−1)(x+1)(x2+1)
(x−1)4(x - 1)^4(x−1)4
(x−1)(x+1)(x2−1)(x - 1)(x + 1)(x^2 - 1)(x−1)(x+1)(x2−1)