x+y分之xy=-2
∴(x+y)/xy=-1/2
1/x+1/y=-1/2 (4)
,y+z分之yz=3分之4
1/y+1/z=3/4 (5)
,z+x分之zx=-3分之4
1/x+1/z=-3/4 (6)
(4)+(5)+(6)得
2/x+2/y+2/z=1/2
1/x+1/y+1/z=1/4
∴(xy+yz+xz)/xyz=1/4
xyz/(xy+yz+xz)=4答案是4！还是-4！是-4我少了一个负号2/x+2/y+2/z=-1/21/x+1/y+1/z=-1/4∴(xy+yz+xz)/xyz=-1/4xyz/(xy+yz+xz)=-4