题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001628-88530.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001628-38738.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-25382.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-81575.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-36947.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-58788.png)
A -2 B 0 C 1 D 2
答案
解析
试题分析:因为a
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001628-38738.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-25382.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-81575.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-36947.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001628-38738.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-36947.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-25382.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-81575.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001628-38738.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-36947.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-25382.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-25382.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-81575.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-25382.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-25382.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-58788.png)
点评:解决此小题的关键是灵活应用等差数列的性质得出a
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001629-25382.png)
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001507-27626.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001507-27626.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001507-36985.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001508-21260.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001508-12326.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001507-27626.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001508-33674.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001310-40967.png)
(Ⅰ)若数列{an}前三项成等差数列,求
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010001310-38267.png)
(Ⅱ)试判断数列{bn}是否为等比数列,并证明你的结论;
(Ⅲ)设0<a<b,Sn为数列{bn}的前n项和.是否存在实数λ,使得对任意正整数n,都有a<Sn<b?若存在,求λ的取值范围;若不存在,说明理由.
A.12 | B.13 | C.14 | D.15 |
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010000813-16496.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010000814-51421.png)
(1)试求
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010000814-60630.png)
(2)猜想
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010000814-15958.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010000752-34186.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010000753-89433.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010000753-40771.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010000753-71602.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010000754-27839.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010000754-62358.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010000754-87454.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010000754-48405.png)
(1)分别求数列
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010000752-34186.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010000754-87454.png)
(2)设
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010000754-99866.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191010/20191010000755-83611.png)
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