Question

 fatorando x^8 - y^4,obtemos

Answer 1

$x^8-y^4= \\ \\ (x^4)^2-(y^2)^2= \\ \\ (x^4+y^2)(x^4-y^2)= \\ \\ (x^4+y^2)((x^2)^2-y^2)= \\ \\ (x^4+y^2)(x^2+y)(x^2-y)$