因式分解填空：x² y四次方 - x四次方 y²=?,4x³-36x=?,2 x四次方 -2=?

x^2y^4-x^4y^2
=x^2y^2(y^2-x^2)
=x^2y^2(y+x)(y-x)
4x^3-36x
=4x(x^2-9)
=4x(x+3)(x-3)
2x^4-2
=2(x^4-1)
=2(x^2+1)(x^2-1)
=2(x^2+1)(x+1)(x-1)