已知x-y=l,xy=2,求x3y-2x2y2+xy3的值.

问题描述:

已知x-y=l,xy=2,求x3y-2x2y2+xy3的值.

∵x-y=l,xy=2,
∴x3y-2x2y2+xy3
=xy(x2-2xy+y2
=xy(x-y)2
=2×1
=2.