x+y=-zx+z=-yy+z=-x故(x+y)(y+z)(x+z）=-xyz=-1
最简单的由x+y+z=0可知，x+y=-zy+z=-xx+z=-y(x+y)(y+z)(x+z）=(-z)(-X)(-y)=-(xyz)已知xyz=1(x+y)(y+z)(x+z）=-1
