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标题: prep1-11 [打印本页]

作者: LilyJune    时间: 2007-8-9 14:12     标题: prep1-11

 

11.  

If p is a positive odd integer, 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.

由条件2也能推出?

怎么考虑的?

谢谢


作者: CasualWalker    时间: 2007-8-10 06:20

如果2对的话,而p是奇数 ,那么p可以写成如下形式:

p= (2a+1)^2+ (2b)^2

a,b地位等同,可以互换

所以p=4*a^2+4*a+1+4*b^2

所以余数是1


作者: LilyJune    时间: 2007-8-11 08:01

many thanks!!




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