a/b=c-d?应该是a/b=c/d则a/c=b/dk=a/c=b/da=ck,b=dk所以(a+c)/(a-c)=(ck+c)/(ck-c)=c(k+1)/c(k-1)=(k+1)/(k-1)(b+d)/(b-d)=(dk+d)/(dk-d)=d(k+1)/d(k-1)=(k+1)/(k-1)所以(a+c)/(a-c)=(b+d)/(b-d)