题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060537-30508.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060538-20881.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060538-11631.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060538-76350.png)
⑴ 求
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060538-45019.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060539-34770.png)
⑵ 求
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060539-68689.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060539-87867.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060539-69954.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060540-39538.png)
解析
试题分析:(1)(1)设该等差数列为
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060540-13094.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060540-39585.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060540-52279.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060541-29386.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060541-28987.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060538-76350.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060541-85837.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060541-36845.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060541-64363.png)
(2)由
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060542-20707.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060542-84101.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060542-63512.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060539-69954.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060543-21547.png)
=
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060543-13765.png)
=
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060540-39538.png)
点评:中档题,在等差数列中,根据已知条件布列首项、公差、项数、末项、前n项和的方程组,是比较常见的题目,对运算能力要求较高。“裂项相消法”是高考重点考查的求和方法之一。
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060526-76589.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060527-57113.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060527-87232.png)
(I) 求数列
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060526-76589.png)
(II) 求数列
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060527-74695.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060520-77026.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060520-47050.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060511-75557.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060511-46481.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060512-96341.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060512-47949.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060512-97831.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060458-59540.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060458-47075.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060458-87493.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060459-26081.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060459-57869.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060447-25392.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060447-35938.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012060448-57850.png)
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