x-y/x+y=2,则xx+2xy+yy/4xy=?

问题描述:

x-y/x+y=2,则xx+2xy+yy/4xy=?

因为x-y/x+y=2
所以(x-y)=2x+2y
所以x=-3y
代入xx+2xy+yy/4xy得
(9yy+2(-3y)y+yy)/(-12yy)=-1/3