计算:x+2y/x-y+2x/y-x-3y/x-y

问题描述:

计算:x+2y/x-y+2x/y-x-3y/x-y

原式=(x+2y)/(x-y)-2x/(x-y)-3y/(x-y)
=(x+2y-2x-3y)/(x-y)
=(-x-y)/(x-y)