∵ z+2x+2y x+y < x+2y+2z y+z < y+2x+2z z+x ,∴ z x+y +2< x y+z +2< y z+x +2∴ z x+y < x y+z < y z+x , x+y z > y+z x > z+x y , x+y z +1> y+z x +1> z+x y +1,即 x+y+z z > y+z+x x > z+x+y y .∴z<x<y故答案为:z<x<y.