Вырожение ( x^2-y^2-z^2-2yz)/( x + y + z ) ( x^2+z^2+2xz-y^2)

(-y^2-2yz-z^2+x^2)/(x+y+z)(x^2+2xz+z^2-y^2) = -(y^2+2yz+z^2-x^2)/(x+y+z)((x+z)^2-y^2)=-((y+z)^2-x^2))/(x+y+z)(x+z-y)(x+z+y)=-(y+z-x)/(x+z+y)(x-y+z)=(x-y-z)/(x+z+y)(x-y+z)