Factor x4−625x^4 - 625x4−625.
(x2−25)(x2+25)(x^2 - 25)(x^2 + 25)(x2−25)(x2+25)
(x−5)(x+5)(x2+25)(x - 5)(x + 5)(x^2 + 25)(x−5)(x+5)(x2+25)
(x−5)2(x+5)2(x - 5)^2(x + 5)^2(x−5)2(x+5)2
(x2−25)2(x^2 - 25)^2(x2−25)2