已知:(x/2)=(y/3)=(z/-7)≠0 求(x+y+z)/(y-z)

问题描述:

已知:(x/2)=(y/3)=(z/-7)≠0 求(x+y+z)/(y-z)

设:(x/2)=(y/3)=(z/-7)=k
x=2k
y=3k
z=-7k
(x+y+z)/(y-z)
=(2k+3k-7k)/(3k+7k)
=-2k/10k
=-1/5