鹰妹， 请帮我做个题

来源: bearsback 于 2010-03-21 19:05:39 [] [博客] [旧帖] [给我悄悄话] 阅读数 : (762 bytes)
本帖于 2010-03-21 20:20:57 时间, 由版主 林贝卡 编辑

two questions:

1. a salesman travels from city A to city B. The distance between A and B is 100 miles. After the man travels 70 miles, he turns back and travels 20 miles towards A.

Question: what is the total distance the man has traveled? how far is he away from B?

2. A salesman travels from city A to city B. The distance between the two cities is 100 miles. If we let x be the distance variable traveled, the time t that it takes him to travel the distance x is
t = (1/225)x^2 - (31/90)x in hours

Question: how many hours does it take the man to travel 90 miles? How many hours does it take the man to get city B （to travel 100 miles)?

now the big question: does 行百里者半九十 mean 1 or 2 or neither?



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