令a=x/y+z=y/x+z=z/x+y则x=a(y+z)y=a(x+z)z=a(x+y)相加x+y+z=2a(x+y+z)所以(2a-1)(x+y+z)=02a-1=0则a=1/2x+y+z=0则y+z=-xa=x/(y+z)=-1所以、(x+y)/z=1/a=2或-1
