题目内容
已知整数的数对列下:
,
,
,
,
,
,
,
,
,
,
,
,…,则第
个数对是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823204916579402.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823204916595468.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823204916626469.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823204916641464.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823204916641468.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823204916657457.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823204916673472.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823204916688503.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823204916719493.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823204916735460.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823204916751453.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823204916751514.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823204916782360.png)
A.![]() | B.![]() | C.![]() | D.![]() |
D
解:规律是:①两个数之和为n的整数对共有n-1个,②在两个数之和为n的n-1个整数对中,排列顺序为,第1个数由1起越来越大,第2个数由n-1起越来越小.设两个数之和为2的数对为第1组,数对个数为1;两个数之和为3的数对为第二组,数对个数2;…,两个数之和为n+1的数对为第n组,数对个数为 n.
又∵1+2+…+10=55,1+2+…+11=66
∴第60个数对在第11组之中的第5个数,从而两数之和为12,应为(5,7);
故答案为(5,7).
又∵1+2+…+10=55,1+2+…+11=66
∴第60个数对在第11组之中的第5个数,从而两数之和为12,应为(5,7);
故答案为(5,7).
![](http://thumb2018.1010pic.com/images/loading.gif)
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