觉得数学答案有误的一道题

daisylala

数学寂静版本较多，我拿的LLsheep的版本看的，http://forum.chasedream.com/dispbbs.asp?boardID=22&ID=406546&page=1

里面15题

    n有几个质因子？

（1）n/5有一个质因子  

（2）3n有两个质因子   

给的答案是E，但是我觉得是C啊，

从1可得n必然是5和某个质数（或质数的若干次方）的乘积，从2得n=3^k  *  某个质数。

结合1、2，n=3^k  *  5 （k不可能等于0，因为n=5的时候，条件1就不满足了）。

所以n应该肯定是有2个质因子的啊。

大家一起来看看啊。

jessie_ning

if n=25  25/5 has one factor,3*25 has two factor,25 has 1 factor
if n=15  15/5 has one factor.3*15 has two factor, 15 has 2 factor , Therefore E is conrect

christinabai

E

ext3

好难啊        z

xs1986

之前还有答案说是d，到底是什么呢

pig2009

以下是引用jessie_ning在2009/9/10 3:44:00的发言：
if n=25  25/5 has one factor,3*25 has two factor,25 has 1 factor
if n=15  15/5 has one factor.3*15 has two factor, 15 has 2 factor , Therefore E is conrect

严重同意！E

chenzheng

我也觉得是E

daisylala

以下是引用jessie_ning在2009/9/10 3:44:00的发言：
if n=25  25/5 has one factor,3*25 has two factor,25 has 1 factor
if n=15  15/5 has one factor.3*15 has two factor, 15 has 2 factor , Therefore E is conrect

谢谢jessie！之前自己没考虑周全，这么说来答案确实是E