由y+1/z=1,得 1/z= 1-y z=1/(1-y)= (1-y+y)/(1-y)= 1+ y/(1-y)将其代入z+1/x=1,得 1+y/(1-y)+1/x = 1则： y/(y-1)=1/x则： x= (y-1)/y= 1- 1/y,即： x + 1/y = 1
