若a+2/3=b/4=c+5/6,且2a-b+3c=21.试求a:b:c.
问题描述:
若
=a+2 3
=b 4
,且2a-b+3c=21.试求a:b:c. c+5 6
答
设
=a+2 3
=b 4
=k,c+5 6
则a=3k-2,b=4k,c=6k-5,
所以,2(3k-2)-4k+3(6k-5)=21,
解得k=2,
所以a=6-2=4,b=8,c=7,
所以a:b:c=4:8:7.