已知x+y=2,xy=2,求1/2x3y+x2y2+1/2xy3的值.
问题描述:
已知x+y=2,xy=2,求
x3y+x2y2+1 2
xy3的值. 1 2
答
x3y+x2y2+1 2
xy3,1 2
=
xy(x2+2xy+y2),1 2
=
xy(x+y)2,1 2
当x+y=2,xy=2时,原式=
×2×22=4.1 2