标题: 请教一题数学题~急求！！ [打印本页] 作者: haidyuan 时间: 2013-1-13 00:46 标题: 请教一题数学题~急求！！ For every positive even interger n, the function h (n) is defined to be the product of all the even integers from 2 to n.If p is the smallest prime factor of h(100)+1, then p is
between 2 and 10 10 20 greater than 40
answer is greater than 40. 求问怎么知道是大于40？？作者: xiaojindiao 时间: 2013-1-13 09:31
根据题目:
h (100)=2x4x6...x100=2^50x1x2x3...50
所以这个 h (100)可以是2-50内任意一个数的整数倍，也就说 h (100)能被2-50内任意一个整数整除。那么 h (100)+1就不能被任意一个2-50内任意一个整数整除，所以 h (100)+1的最小质因子一定是大于50的数，具体是多少就不用管了，说不定它就是个质数呢作者: dszdspc 时间: 2013-1-25 13:48
顶顶顶！纠结了半天终于懂啦作者: dayxin 时间: 2015-6-4 08:49
太猛了啊~~
