Question

factorise x has a power 4 - y has a power 4

Answer 1

x^4-y^4
(x^2+y^2)(x^2-y^2)
(x^2+y^2)(x+y)(x-y)

Answer 2

Given, x^4 - y^4

          = (x^2)^2 - (y^2)^2 

          = (x^2 + y^2)(x^2 - y^2)

          =  (x^2+ y^2)(x + y)(x - y).


Hope this helps!