Question

已知x+y+z=1,xy+yz+zx=xyz,求证：（1-x）(x+yz)=0 ,(1-y)(y+zx)=0,(1-z)

Answer 1

(1-x)(x+yz)=(y+z)(x+yz)=xy+xz+yz(y+z)=xyz-yz+yz(y+z)=xyz-yz(1-yz)=xyz-xyz=0

其他一样.