已知 x+y+z=3x+y+z=3x+y+z=3 , (x−1)3+(y−1)3+(z−1)3=0(x-1)^3+(y-1)^3+(z-1)^3=0(x−1)3+(y−1)3+(z−1)3=0
求证 x,y,zx,y,zx,y,z 中至少有一个数为 1
