题目
题型:不详难度:来源:
设各项均为正数的数列
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010618-72527.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010618-68493.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010618-56467.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010618-68731.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010618-19305.gif)
(1)求数列
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010618-72527.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010619-32450.gif)
(2)设
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010619-15317.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010619-78451.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010619-69252.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010619-54397.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010619-15317.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010620-83159.gif)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010620-19926.gif)
(2)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010620-53792.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010619-15317.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010620-83159.gif)
解析
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010620-32704.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010621-31466.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010621-85739.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010621-96226.gif)
化简,得:
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010621-66097.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010621-36625.gif)
当
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010622-65310.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010622-26350.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010622-28801.gif)
故所求
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010620-19926.gif)
(2)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010622-81046.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010623-17147.gif)
又
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010619-78451.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010623-82452.gif)
故
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010620-53792.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010619-15317.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010620-83159.gif)
核心考点
试题【(本小题满分12分)设各项均为正数的数列的前n项和为,已知,数列是公差为的等差数列。(1)求数列的通项公式(用表示);(2)设为实数,对满足的任意正整数,不等式】;主要考察你对等差数列等知识点的理解。[详细]
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010600-28955.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010600-58143.gif)
(1)求
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010601-92808.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010601-86208.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010601-45944.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010545-22034.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010545-56503.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010545-22034.gif)
A.充分而不必要条件 | B.必要而不充分条件 |
C.充分必要条件 | D.既不充分也不必要条件 |
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010539-23600.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010539-57518.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010539-45053.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010539-68619.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010539-95390.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010540-31979.gif)
A.
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010540-39251.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010540-86180.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010540-51429.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010540-88100.gif)
设{an}是等差数列,{bn}是各项为正项的等比数列,且a1=b1="1," a3+b5="21," a5+b3=13.
(1)求{an}, {bn}的通项公式;
(2)求数列{
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010525-96666.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010520-99515.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191013/20191013010520-38796.gif)
A.7 | B.14 | C.21 | D.42 |
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