Преобразовать в многочлен. (x+y-z)(x-y+z)-(x+y+z)(x-y-z)
(x²-xy+xz+xy-y²+yz-xz-yz-z²)-(x²-xy-xz+xy-y²-yz+zx-zy-z²)=x²-y²-z²-x²+y²+z²=0.