一.x-y=2,则x²-2xy+y²= 二.x-y=-1,xy=3,则x³y-2x²y²+xy³=
问题描述：
一.x-y=2,则x²-2xy+y²= 二.x-y=-1,xy=3,则x³y-2x²y²+xy³=
答
x²-2xy+y²
=(x-y)²
=2²
=4
x³y-2x²y²+xy³
=xy(x²-2xy+y²)
=xy(x-y)²
=3*(-1)²
=3