Factor completely: x4−5x2+4x^4 - 5x^2 + 4x4−5x2+4.
(x2−1)(x2−4)(x^2 - 1)(x^2 - 4)(x2−1)(x2−4)
(x−1)(x+1)(x−2)(x+2)(x - 1)(x + 1)(x - 2)(x + 2)(x−1)(x+1)(x−2)(x+2)
(x2+1)(x2−4)(x^2 + 1)(x^2 - 4)(x2+1)(x2−4)
Both (a) and (b)