2x^3-x^2z-4x^2y+2xyz+2xy^2-y^2z因式分解,要用主元法做

2x^3-x^2z-4x^2y+2xyz+2xy^2-y^2z
因式分解,要用主元法做

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