Question

A、B两地间的距离为36km,甲从A地,乙从B地同时出发相向而行,两人相遇后,甲再走2小时30分到达B地,乙再走1小时3

Answer 1

1）设甲乙速度分别为x,y千米/小时

5x/2+8y/5=36,

（5x/2）/y=（8y/5）/x

x=8/5,y=2,

2）n(n-3)/2=14,

n=7

3)

(50+x)(500-10x)=8000,

10(50+x)(50-x)=8000

2500-x^2=800,

x^2=1700,

x=10√17,-10√17