3(X^2+Y^2+Z^2)=(X+Y+Z)^2,求证:X=Y=Z.解3x*2+3y*2+3z*2=x*2+y*2+z*2+2xy+2xz+2yz3x*2-x*2+3y*2-y*2+3z*2-z*2-2xy-2xz-2yz=0（x*2+y*2-2xy）+（x*2+z*2+2xz）+（y*2+z*2+2yz）=0（x-y）*2+（x-z）*2+（z-y）*2=0因为...