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