马上要考了，PREP上很多题不会啊。。救命

1).If n and t are positive intergers, what is the greatest prime factor of the product nt?

   (1). The greatest common factor of n and t is 5.

   (2). The least common multiple of n and t is 105.

这种题怎么做啊？

 2). If p is a positive odd interger, what is the remainder when p is divided by 4?

  (1).when p is divided by 8, the remainder is 5.

  (2). p is the sum of the squares of two positive integers.

 3). 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

 4). Six countries in a certain region sent a total of 75 representatives to an international congress, and no two countries sent the same number of representatives. of the six countries, if country A sent the second greatest number of representatives, did country A send at least 10 representatives？

  (1).one of the six countries sent 41 representatives to the congress

  (2).country A sent fewer than 12 representatives to the congress

帮帮忙啊

n,t正整数，nt的最大质因子是？(前提是否应该有个nt互质阿？)

(1)最大公约数5 (2)最小公倍105

解法:nt=5*105=(5*3)*(5*7)=15*35,最大的就是7

answer:C

update:这道题想明白了，nt=K*105=(3^x)*(5^y)*(7^z) 所以最大的质因子是7，ans=B

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(1)P=8K+5=4*2K+5=4*(2K+1)+1        sufficient

(2)P=x^2+y^2, 不知道该怎么求，只能带入，x=2,y=3;x=2,y=4,分别带入，no sufficient

answer:A

update:  (2) P为两个数的和，那么这两个数x^2,y^2必为一奇一偶，那么x,y也必须为一奇一偶。P=(2M)^2+(2N+1)^2=4M^2+4N^2+4N+1,余数为1。ans：D

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(1)3^(m+10), m=1,2,3,4, no sufficient

(2)3^(4n+3)=27*(3^4n),    3^n可以算出末位数为(3,9,7,1),3^4n=81^n,末位=1，所以原题只要看27除10即可，

answer=B

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(1)送41人的肯定是最多的了，那么剩下5个国家送了34，最多的是A，

    设A=9，那么，B，C，D，E分别为5，6，7，8，S=5+6+7+8+9=35>34，也就是说，A如果小于10，也成立，     no sufficient

(2) no sufficient

两个连立，也不行

answer:E

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不知道对不对，大家排砖哦

第一个是B，第二个是D。后面两个是对的。

还有没有人帮忙解答啊？

想了一下，发现自己没有掌握考点。

现在应该对了

要怎么掌握考点啊，我满多都还不会做啊，怎么办啊？

以前没发现自己数学这菜啊，看似简单的题目。。。不会