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求助一道prep的数学题,最怕这种题了

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楼主
发表于 2010-1-29 21:14:45 | 只看该作者 回帖奖励 |正序浏览 |阅读模式
For every positive even integer n, the function h(n) is defined to be the product of all the even integers from 2 to n, inclusive.  If p is the smallest prime factor of h(100) + 1, then p is

(A) between 2 and 10
(B) between 10 and 20
(C) between 20 and 30
(D) between 30 and 40
(E) greater than 40
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地板
 楼主| 发表于 2010-1-29 23:05:15 | 只看该作者
对,选e,我再仔细看看的
谢拉
板凳
发表于 2010-1-29 22:39:33 | 只看该作者
给你一个google来的解题过程,

h(100)= 2*4*6............100
h(100)+1=2*4*6............100 +1
2(1*2*3.......50)+1

so when h(100)+1 is divided by any of the nos between 2 and 50 will leave a remainder 1.

2*50!+1 will not be divisible by any no <50

answer E
沙发
发表于 2010-1-29 22:35:05 | 只看该作者
选e?
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