[分享]wyf007的数学题讨论贴

wyf007 · 发表于 2009-3-26 19:29:00

我相信有不少同学在这个网上像我一样,没有接触数学有快10年了.好了,现在让我们一起讨论一下数学题.

How many multiples of 4 are there between 12 and 96, inclusive?

A. 21

B. 22

C. 23

D. 24

E. 25

Answer: B

有谁能帮我解释一下吗?

wyf007 · 发表于 2009-3-26 19:32:00

If x>3,000, then the value of X/(2X+1) is closest to:

A. 1/6

B. 1/3

C. 10/21

D. 1/2

E. 3/2

Answer: D

Can anyone please help me on this?

erikajin · 发表于 2009-3-26 20:06:00

How many multiples of 4 are there between 12 and 96, inclusive?

96/4=24, 即比96小的数中有24个4 的倍数

比12小的有两个，所以是24

If x>3,000, then the value of X/(2X+1) is closest to:

x足够大时 x/2x+1 近似等于 x/2x

wyf007 · 发表于 2009-3-27 00:33:00

Thank you very much for your explanation. I do believe that yours does help other people who may be in doubts about this.

skyhai1981 · 发表于 2009-3-27 04:45:00

第一题根据等差数列n=(an-a1)/d +1 得出n=(96-12)/4 +1=21+1=22

第二题上下同除x，得1/(2+1/x),因为x>3000，所以1/x无限趋于0，因此近似为1/2.

理解呀，我也是工作多年，数学都就饭吃了！跟在校生无法比！

[此贴子已经被作者于2009-3-27 4:45:39编辑过]

所属分类: GMAT考试