若x:y:z=2:3:4,求x+y+z/x-2y+3z的值

问题描述:

若x:y:z=2:3:4,求x+y+z/x-2y+3z的值

x:y:z=2:3:4
令x=2k,y=3k,z=4k
(x+y+z)/(x-2y+3z)
=(2k+3k+4k)/(2k-2*3k+3*4k)
=9k/(8k)
=9/8