已知x-y=-1,xy=3,求x^3y-2x^2y^2+xy^3

已知x-y=-1,xy=3,求x^3y-2x^2y^2+xy^3
已知x-y=-1,xy=3,求x^3y-2x^2y^2+xy^3

已知x-y=-1,xy=3,求x^3y-2x^2y^2+xy^3
x^3y-2x^2y^2+xy^3=xy(3x^2-4xy+y^2)=xy(3x-y)(x-y)
x-y=-1,xy=3 y(y-1)=3

x³y-2x²y²+xy³
=xy(x²-2xy+y²)
=xy(x-y)²
=3•(-1)²
=3