求教一道prep数学题

ivydaodao

For every positive even intgers, the function h(n) is defined to be the product of all the even intgers 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 20and 30
d.between 30and 40
e.greater than 40

选e

jyzywing

2*50!+1 前面50个数连续相乘 最后还加1，最小质数一定比50还大

lhz910216

h(100)+1=2*4*6.......*100+1
=2^50 *(1*2*3*...*50)+1
所以h（100）的话除以50以内的任何数都可以整除，h(100)+1除以50以内任何数都会余1，所以了~p要大于50
选E啦~~~~~~~~~

宁祭

刚好也做到这道题纠结了半天！！！多谢楼上解答！！好人一生平安！

ivydaodao

jyzywing 发表于 2013-8-17 15:10
2*50!+1 前面50个数连续相乘 最后还加1，最小质数一定比50还大

非常感谢！！！！！！！！！