Question

(x-y) (x+y) (x^2+y2)(x^4+y^4)-x^8=-y^8

Answer 1

(x-y) (x+y)=x^2-y^2
(x^2+y2) (x^2-y^2)=x^4-y^4
(x^4-y^4)(x^4+y^4)=x^8-y^8
x^8-y^8-x^8=-y^8