x-3=y-2=z-1则x-y=3-2=1y-z=2-1=1z-x=1-3=-2所以x²+y²+z²-xy-yz-xz=(2x²+2y²+2z²-2xy-2yz-2xz)/2=[(x²-2xy+y²)+(y²-2yz+z²)+(z²-2xz+x²)]/2=[(x-y)&su...