2/(x+y)+5/(x-y)=-8,9/(x+y)-10/(x-y)=-11 他舅近来帮忙下
问题描述：
2/(x+y)+5/(x-y)=-8,9/(x+y)-10/(x-y)=-11 他舅近来帮忙下
答
1/(x+y)=a
1/(x-y)=b
则2a+5b=-8 (1)
9a-10b=-11 (2)
(1)*2+(2)
13a=-27
a=-27/13
b=-1194/65
所以
x+y=-13/27
x-y=-65/1194
相加,求出x
相减,求出y