Question

Factor the following expression completely
X4-y4

Answer 1

$x^4-y^4=\left(x^2\right)^2-\left(y^2\right)^2=(x^2-y^2)(x^2+y^2)=(x-y)(x+y)(x^2+y^2)\\\\\\a^2-b^2=(a-b)(a+b)$

Answer 2

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

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

3)(x-y)^4
=x^4-4x^3y+6x^2y^2-4xy^3+y^2

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