若x/3=y/4=z/5≠0,求2x+y+3z/3x-2y-z的值.

问题描述:

若x/3=y/4=z/5≠0,求2x+y+3z/3x-2y-z的值.

令x/3=y/4=z/5=k,那么x=3k,y=4k,z=5k
2x+y+3z/3x-2y-z=(6k+4k+15k)/(9k-8k-5k)
=25k/(-4k)
=-25/4

令x/3=y/4=z/5≠0=k
x=3k,y=4k,z=5k
代入得
(2x+y+3z)/(3x-2y-z)
=(6+4+15)/(9-8-5)
=-25/4