已知2x2-xy-3y2=0,求x−yx+y的值.

问题描述:

已知2x2-xy-3y2=0,求

x−y
x+y
的值.

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

x−y
x+y
=
3y
2
−y
3y
2
+y
=
y
5y
=
1
5