已知2x2-xy-3y2=0,求x−yx+y的值.
问题描述:
已知2x2-xy-3y2=0,求
的值. x−y x+y
答
2x2-xy-3y2=0,
(2x-3y)(x+y)=0,
解得:2x-3y=0或x+y=0(分母为0,舍去),
解得:x=
,3y 2
则
=x−y x+y
=
−y3y 2
+y3y 2
=y 5y
.1 5