已知x/2=y/3=z/4,求x²+2y²+3z²/xy+yz-zx对了，学的这章是分式，请用“分式”来解答，

已知x/2=y/3=z/4,求x²+2y²+3z²/xy+yz-zx
对了，学的这章是分式，请用“分式”来解答，

令x/2=y/3=z/4=k,则有
x=2k,y=3k,z=4k
所以x²+2y²+3z²/xy+yz-zx
=4k²+18k²+48k²/6k²+12k²-8k²
=70k²/10k²
=7