(x^2+1)^2-4 x^2
(x^2+1)^2-4 x^2 = (x^2+1)^2-(2 x)^2:
(x^2+1)^2-(2 x)^2
(x^2+1)^2-(2 x)^2 = ((x^2+1)-2 x) ((x^2+1)+2 x):
(x^2-2 x+1) (x^2+2 x+1)
x^2+2 x+1 = (x+1) (x+1):
(x+1) (x+1) (x^2-2 x+1)
(x+1) (x+1) = (x+1)^2:
(x+1)^2 (x^2-2 x+1)
x^2-2 x+1 = (x-1) (x-1):
(x-1) (x-1) (x+1)^2
(x-1) (x-1) = (x-1)^2:
Ответ: (x-1)^2 (x+1)^2