第2章 等比数列
2.3 等比数列(基础练)
一、选择题:在每小题给出的四个选项中,只有一项是符合题目要求的.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d229a8bdd3d468d87adb9b04cde1b59.png)
A.1 | B.﹣1 | C.2019 | D.﹣2019 |
【知识点】 等比数列通项公式的基本量计算 求等比数列前n项和
A.1 | B.±1 | C.![]() | D.![]() |
【知识点】 等比数列下标和性质及应用
A.48 | B.64 | C.72 | D.96 |
【知识点】 等比数列通项公式的基本量计算 等比数列下标和性质及应用
A.a2+a3>b2+b3 |
B.a2+a3<b2+b3 |
C.a2+a3=b2+b3 |
D.a2+a3与b2+b3的大小不确定 |
【知识点】 等差数列通项公式的基本量计算 等比数列通项公式的基本量计算
二、填空题
【知识点】 求等比数列前n项和
三、解答题
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b065334d8f60c49f4bd3d9f1373fe4cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f639aa2fde8c717aa78e22e13daab1c4.png)
(1)求证:数列{an+n}为等比数列;
(2)求数列{an}的通项公式.
【知识点】 由递推关系式求通项公式 由递推关系证明等比数列
(1)已知a1=13,q=﹣2,求a6;
(2)已知a3=20,a6=160,求Sn
【知识点】 等比数列通项公式的基本量计算 求等比数列前n项和
(1)求数列{an}的通项公式;
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c0f6000421c5370e4b89f23be199f388.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30c5c2d777efa6bd6e832b5755f8e436.png)
【知识点】 写出等比数列的通项公式 等比数列前n项和的基本量计算 裂项相消法求和
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5562f79331969db91fc32bc4f775c650.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/28d82e4c2294efbd33e1b268e9a0cec5.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e72adb45c60c2f63b46e65ff787302bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e88093a749c0d46e0ee931ecfaff925.png)
(2)求证:数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(3)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
【知识点】 由递推关系证明等比数列 前n项和与通项关系
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a5d1db73e354c7f0e22ef90b7c1bc878.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca5ac132a913d3cc9e79361993840a83.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5cfb19f0c37a72b33083ae9319f11a74.png)
(1)求证:数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a5251e4259930126400dac30b389afe0.png)
(2)不等式
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be15eb8dc7308ae19412125703bd07e0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36b98ef143f8159f3a7dafa1fd2f2370.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
【知识点】 由递推关系证明等比数列 分组(并项)法求和 数列不等式恒成立问题