Question

因式分解:x^2(x^2-y^2)-12y^4

Answer 1

原式=x^4-x^2y^2-12y^4

=x^4-9y^4-x^2y^2-3y^4

=(x^2-3y^2)(x^2+3y^2)-y^2(x^2+3y^2)

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

=(x^2+3y^2)(x-2y)(x+2y)