[求助]2道MATH~^O^ 给笨笨的我引导下THX

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·How many different prime numbers are factors of the positive integer n ?

(1) Four different prime numbers are factors of 2n.                                     
(2) Four different prime numbers are factors of n^2 .

答案是：B   寻求思路？

 

·If n and m are positive integers, what is the remainder when 3^(4n + 2 + m) is divided by 10 ?
    

(1)n=2

(2)m=1

答案是B？ WHY?

mymengming

周一考试，还没看，不能详细回复，见谅
1
（1）n含不含有有2这个prim factor会导致prime factor 数量不同
（2）n含有几个prime factor， n^2就含有多少个
选B

2
3^0=1
3^1=3
3^2=9
3^3=7
3^4=1
……
4个一循环
（1）n=2不能说明4n + 2 + m是奇数还是偶数，有4个答案
（2）n等于多少对3^(4n+2+m)的结尾数字没有影响，因为4个一循环，所以2+m决定了结尾时多少
选B

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感动一下，谢谢你~~

经你一说还真豁然开朗了，恩，要踏踏实实地学习了。

祝兄台考试顺利~