[求助]help!!!

krissyyang

prep里的一道题，大意如下：

n为任意正偶数，h（n)表示从2到n的正偶数乘积。若p是h（100）+1的最小质因子，p的范围是：

2~10   ； 10~20  ； 20~30  ； 30~40 ；  >40.

答案是10~20.

哪位NN帮帮忙啊~~

krissyyang

自己顶顶~~~

hang13

243. 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, the p is?

Greater than 40 ( i am not sure at all）

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
            

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
ANS E

hang13

prep的题 一般testmagic 都可以搜索到的