名校
解题方法
1 . 定义1 进位制:进位制是人们为了计数和运算方便而约定的记数系统,约定满二进一,就是二进制:满十进一,就是十进制;满十二进一,就是十二进制;满六十进一,就是六十进制;等等.也就是说,“满几进一”就是几进制,几进制的基数就是几,一般地,若
是一个大于1的整数,那么以
为基数的
进制数可以表示为一串数字符号连写在一起的形式![](https://staticzujuan.xkw.com/quesimg/Upload/formula/524f146ae1dcf0aa3e8d526945238342.png)
进制的数也可以表示成不同位上数字符号与基数的幂的乘积之和的形式.如
.
定义2 三角形数:形如
,即
的数叫做三角形数.
(1)若
是三角形数,试写出一个满足条件的
的值;
(2)若
是完全平方数,求
的值;
(3)已知
,设数列
的前
项和为
,证明:当
时,
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/524f146ae1dcf0aa3e8d526945238342.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5056dd0d5ad0eff9e95291b04d3553b1.png)
定义2 三角形数:形如
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73590d366136e56ab9a92db739b0762d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a46706761370c3a424c0ca83906f0f6.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/694c82f33ec815778a6d49bfdcd1628b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a48c2531616a8dfbbc06a97868b72cc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
(3)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/571561f8606c5f39c4cd4f64d2d44aa1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57ef6d44448092ebdb9e4a49d866a749.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/029da2067b3564cee13879e402a89a01.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21510d169a75d5f8b50e985aac26fe70.png)
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