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miafy

7.  905-!-item-!-187;#058&000575

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

答案是Ｅ

Princesseve

ding!

我也不明白这题是怎么回事

mswlove

有谁可以解答啊，我也没有一点头绪啊

winterain

我也不会，还在到处问人呢。

winterain

我google了半天，现在试着来解释下。就是h(100)=2^50*(1*2*3*...*50)，那么从1到50都是h(100)的factor,那么1到50就不可能是h(100)+1的factor,也就是说h(100)+1的factor最小也也是 大于50 的.

既然the smallest factor〉50，那么必然the smallest prime factor>50。所以选E。

写的有点乱，希望lz能看懂。

mymengming

请搜索
http://forum.chasedream.com/dispbbs.asp?BoardID=22&replyID=1733108&id=183630&skin=0