请教GMATPrep Practice I Q Q3

GarfieldCao

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.     2<<10

B.      10<<20

C.      20<<30

D.     30<<40

E.      P>40

thy5438

我记得好象选E吧,H(100)的话,后面有N多个0,再加个1,直觉上来说不能被这么小的质数除开的...

基本没有合理的思路,同LZ求教

GarfieldCao

刚刚在坛子里找到了sunjin1988 同学贴的思路,觉得很有道理:

"这是我在网上搜的
            h(100) = 2 x 4 x . . . x 100 = (2^50)x 50!.  Therefore, the integers 2, 3, 4, . . . , 50 are all factors of h(100), which means that none of these integers can be a factor of h(100) + 1.  Thus the smallest prime factor of h(100) + 1 must be greater than 50.希望有用 好像跟47一点关系都没"

GarfieldCao

其实也不能说跟47一点扯不上关系,因为47其实是50以内最大的质数了