Question

已知x+y=-4,xy=-12,求（y+1)／(x+1)+(x+1)／（y+1)的值。

Answer 1

有x+y=-4,
xy=-12,
联立方程组,可以解得
x=2
时
y=-6
x=
-6时
y=2
代入（y+1)／(x+1)+(x+1)／（y+1)解得:
结果=-12/5
(楼主啊,我游戏打一半专门停下来给您解题,加点分吧..)

Answer 2

x²+y²=(x+y)²-2xy=(-4)²-2×(-12)=40
(y+1)/(x+1)+(x+1)/(y+1)
通分得
=[(y+1)²+(x+1)²]/[(x+1)(y+1)]
展开得
=[y²+2y+1+x²+2x+1]/(xy+x+y+1)
=[(x²+y²)+2(x+y)+2]/[xy+(x+y)+1]
代入已知量
=(40+2×(-4)+2)/(-12+(-4)+1)
=34/(-15)
=-34/15