题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043129-28142.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043129-88964.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043129-61190.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043129-80861.png)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043129-88964.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043129-61190.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043129-80861.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043130-50264.png)
解析
试题分析:假设
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043129-88964.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043129-61190.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043129-80861.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043130-50264.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043130-15288.png)
∵a、b、c成等差数列且公差
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043129-28142.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043130-14164.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043130-61080.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043131-83741.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043131-45032.png)
假设为谬,故原命题获证。
点评:中档题,反证法就是从反论题入手,把命题结论的否定当作条件,使之得到与条件相矛盾,肯定了命题的结论,从而使命题获得了证明。在应用反证法证题时,一定要用到“反设”,否则就不是反证法。
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043112-46887.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043112-94385.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043112-71182.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043112-90599.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043113-92702.png)
(Ⅰ)求数列
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043112-46887.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043113-36146.png)
(Ⅱ)猜想数列
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043112-46887.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043113-97654.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043102-55140.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043102-40448.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043102-77563.png)
A.3 | B.![]() | C.2 | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043041-24912.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043042-69052.png)
(Ⅰ)求
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043042-80945.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043042-54652.png)
(II)若
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043042-32225.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043042-33577.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043043-28345.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043033-42738.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043033-22568.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043033-35571.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043033-34312.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043034-72463.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043034-91823.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043034-55423.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043034-25592.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043033-42738.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043035-47036.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043034-25592.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043035-47036.png)
A.37和38 | B.38 | C.37 | D.36和37 |
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043012-39133.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043012-49488.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043012-44167.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043012-31734.png)
(1)求数列
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043012-39133.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043013-74049.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043012-49488.png)
(2)令
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043013-74336.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043013-35202.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043013-15235.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043013-26005.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191012/20191012043014-13328.png)
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