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