题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065129-17089.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065129-99258.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065130-32014.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065130-47691.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065130-76090.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065130-39912.png)
(Ⅰ)求数列
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065131-54363.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065130-76090.png)
(Ⅱ)设数列
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065131-96510.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065131-31998.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065131-27921.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065132-33258.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065132-70378.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065132-54132.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065132-38408.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065132-20853.png)
(2)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065133-46071.png)
解析
试题分析:.(Ⅰ)∵a2=1+d ,a5=1+4d ,a14=1+13d,且a2、a5、a14成等比数列
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065133-11780.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065132-38408.png)
又∵
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065133-97099.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065132-20853.png)
(Ⅱ)∵
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065131-27921.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065132-33258.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065133-32895.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065133-53021.png)
又
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065131-27921.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065134-73751.png)
①-②:
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065134-29984.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065134-60099.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065134-34316.png)
则
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065135-45735.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065135-49762.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065135-26057.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065135-70673.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065133-46071.png)
点评:求解数列的通项公式主要是求解基本元素首项和公差(或公比),同时能利用整体的思想求解数列的通项公式,结合求和方法得到结论,属于基础题。
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065114-78656.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065115-45035.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065115-22408.png)
(Ⅰ)求数列
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065114-78656.png)
(Ⅱ)设数列
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065115-17750.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065115-54844.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065116-40325.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065116-47746.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065116-71578.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065116-21360.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065107-35597.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065107-79457.png)
A.13 | B.26 | C.52 | D.156 |
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065059-33458.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065059-72811.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065100-22059.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065100-42177.png)
A. 13 | B. 14 | C. 15 | D. 14或15 |
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065036-10547.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065037-84817.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065037-98229.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065037-70945.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065036-10547.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065037-70945.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065037-56756.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065037-56885.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065038-36490.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065038-41018.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065038-88417.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065036-10547.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065038-61835.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065036-10547.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065039-11657.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065036-10547.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065039-17522.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065039-21662.png)
其中所有真命题的序号是_________________.
已知数列
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012064951-40246.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012064951-81889.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012064951-28600.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012064952-45005.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012064952-45437.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012064952-46330.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012064952-46436.png)
(1) 求数列
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012064951-40246.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065010-76741.png)
(2) 设
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065010-54084.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012064951-40246.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065010-54948.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065010-87706.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065011-25170.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065011-25079.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065011-35286.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012065010-87706.png)
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