做一个：根据题意得x-3=0y+1=0z=0∴x=3 y=-1 z=0 1)x²+y²+ z²-xy-yz-xz=9+1+0+3=132)原式=1/2[(3+1)²+(-1-0)²+(3-0)²]=133)结果相等结论：x²+y²+ z²-xy-yz-xz=1/2[(x-y)²+(y-z)²+(z-x)²]
