4x²/(x-y)(x-z)+4y²/(y-z)(y-x)+4z²/(z-x)(z-y)
=4x²(y-z)/(x-y)(x-z)(y-z)-4y²(x-z)/(x-y)(x-z)(y-z)+4z²(x-y)/(x-y)(x-z)(y-z)
=[4x²(y-z)-4y²(x-z)+4z²(x-y)]/(x-y)(x-z)(y-z)
4x²/(x-y)(x-z)+4y²/(y-z)(y-x)+4z²/(z-x)(z-y)
=4x²(y-z)/(x-y)(x-z)(y-z)-4y²(x-z)/(x-y)(x-z)(y-z)+4z²(x-y)/(x-y)(x-z)(y-z)
=[4x²(y-z)-4y²(x-z)+4z²(x-y)]/(x-y)(x-z)(y-z)