题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223738-20719.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223739-53629.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223739-46238.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223739-89472.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223740-37881.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223740-17499.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223740-61052.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223740-82854.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223741-67616.png)
(Ⅰ)求数列
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223738-20719.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223740-17499.png)
(Ⅱ)设数列
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223738-20719.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223740-61052.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223741-94748.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223741-99265.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223741-45114.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223741-45297.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223742-57528.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223742-16482.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223742-93274.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223743-78745.png)
解析
解:(Ⅰ)由
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223743-46628.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223743-95502.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223743-20793.png)
从而
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223744-17603.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223742-16482.png)
在已知
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223744-31428.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223744-71903.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223744-51101.png)
当
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223745-45152.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223744-31428.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223745-41994.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223745-70032.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223745-45307.png)
(Ⅱ)∵
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223746-34366.png)
则
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223746-57711.png)
当
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223745-45152.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223746-22999.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223746-45086.png)
有
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223747-11341.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223747-59237.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223747-34559.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223747-39222.png)
则有
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223743-78745.png)
核心考点
试题【已知等差数列的公差大于0,且、是方程的两根.数列的前项和为,满足(Ⅰ)求数列,的通项公式;(Ⅱ)设数列的前项和为,记.若为数列中的最大项,求实数的取值范围.】;主要考察你对数列的概念与表示方法等知识点的理解。[详细]
举一反三
A.6 | B.7 | C.8 | D.9 |
A.5 | B.6 | C.7 | D.8 |
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223538-31892.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223539-24566.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223524-23811.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223525-35838.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223525-45389.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223111-52893.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223111-28229.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191007/20191007223111-37960.png)
A.![]() | B.![]() |
C.![]() | D.![]() |
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