设a-b/x=b-c/y=c-a/z=k,
∴x=a-b/k,y=b-c/k,z=c-a/k,
∵x+y+z=a-b/k+b-c/k+c-a/k,
且a-b/k+b-c/k+c-a/k=0,
∴x+y+z=0
我前几天刚刚做过这道题,应该是这样的.