x-y/x+y=-1/2,x*x-xy-2y*y/x*x-3xy+2y*y的解是多少?
问题描述：
x-y/x+y=-1/2,x*x-xy-2y*y/x*x-3xy+2y*y的解是多少?
同上,请将过程写出,
答
x*x-xy-2y*y/x*x-3xy+2y*y
=(x-2y)(x+y)/(x-2y)(x-y)
=(x+y)/(x-y)
=-2