已知x:y:z=2:3:4,求xy-xz-x²/x-2xy+y²-z²的值
问题描述：
已知x:y:z=2:3:4,求xy-xz-x²/x-2xy+y²-z²的值
答
分母漏掉一个平方吧 (xy-xz-x²)/(x²-2xy+y²-z²)
根据题意,可得
令x=2k y=3k z=4k (k≠0)
于是
(xy-xz-x²)/(x²-2xy+y²-z²)
=(6k²-8k²-4k²)/(4k²-12k²+9k²-16k²)
=(-6k²)/(-15k²)
=6/15
=2/5