Factor x4−16x^4 - 16x4−16.
(x2−4)(x2+4)=(x−2)(x+2)(x2+4)(x^2 - 4)(x^2 + 4) = (x-2)(x+2)(x^2+4)(x2−4)(x2+4)=(x−2)(x+2)(x2+4)
(x−4)2(x+4)2(x - 4)^2(x + 4)^2(x−4)2(x+4)2
(x2−8)(x2+2)(x^2 - 8)(x^2 + 2)(x2−8)(x2+2)
(x−4)(x+4)(x-4)(x+4)(x−4)(x+4)