题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091448-99779.png)
(1)求{an}的通项公式;
(2)若Cn=an·bn,求数列{Cn}的前n项和Sn。
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091449-96045.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091449-38954.png)
解析
试题分析:(1)由首项
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091449-60998.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091449-52234.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091450-91503.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091449-96045.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091450-44311.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091450-70956.png)
试题解析:(1)由题意知:
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091449-52234.png)
即
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091450-68894.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091450-65010.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091450-91503.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091450-60308.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091449-96045.png)
(2)由题意
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091450-43919.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091451-32751.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091450-44311.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091450-70956.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091451-47516.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091451-63594.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091450-60308.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091451-23549.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091452-45076.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091449-38954.png)
核心考点
试题【已知数列{an}是首项为-1,公差d 0的等差数列,且它的第2、3、6项依次构成等比数列{bn}的前3项。(1)求{an}的通项公式;(2)若Cn=an·bn,】;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/20191009/20191009091336-78820.png)
(1)求{an}的通项公式;
(2)若Cn=an·bn,求数列{Cn}的前n项和Sn。
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091059-45949.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091100-69472.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091100-56883.png)
(Ⅰ)求数列
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091059-45949.png)
(Ⅱ)设
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091100-44938.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091100-18808.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091101-53132.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091101-53132.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091042-52078.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091042-48123.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091042-96676.png)
A.1024 | B.2003 | C.2026 | D.2048 |
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091010-91139.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091010-53131.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009091010-90372.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009090922-63438.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009090922-84540.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009090923-74138.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009090923-34717.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191009/20191009090923-92110.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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