设
是等比数列,且
,证明数列
是等差数列,并求出这个等差数列的首项与公差.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9645bd4d2002993b90ec6d48f9c04f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4711944aa361bd9f2ed566b24c6888ec.png)
20-21高二·全国·课后作业 查看更多[2]
更新时间:2021-11-05 09:00:27
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相似题推荐
【推荐1】在数列
中,
,若平面向量
与
平行,则在①
,
;②
,
;③
,
这三个条件中任选一个,求数列
的通项公式.注:如果选择多个条件分别解答,按第一个解答计分.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/039e4fe671d61e59b96ee525c9df43e8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82be4de56b8ed6bb5aeb661da2c87008.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83671fe98e700015b2fa8d8b7f53a8a3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27f830dfaeb1daa97332bedb0d738e73.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dcc9a57bb44653938da92746ceb697e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbca3fc0865b1db635a1550038df38d8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5140d07b2e65620f416479d7cbb77a0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d31f463c4f8f9fc354cabafcaa51c93.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/898dfa93a376a275815751a3a87f00a3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
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【推荐2】若等比数列
的前
项和为
,且
,
.
(Ⅰ)求
,
;
(Ⅱ)求数列
的前
项和. 判断
,
,
是否为等差数列,并说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://img.xkw.com/dksih/QBM/2018/11/16/2076853932802048/2078897907908608/STEM/8efad189eb5d4115ba7317b0483cc045.png?resizew=13)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6df1038200f2d97a52c716aab6c3bcb6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a9875b5a21e007035dbf079af4617d3b.png)
(Ⅰ)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e72adb45c60c2f63b46e65ff787302bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e88093a749c0d46e0ee931ecfaff925.png)
(Ⅱ)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://img.xkw.com/dksih/QBM/2018/11/16/2076853932802048/2078897907908608/STEM/5a272b40315e406a95333649caea414b.png?resizew=14)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a401c246d2e11b9f687de2cba56f740.png)
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解题方法
【推荐1】已知
为等差数列,
,记
,
分别为数列
,
的前n项和,
,
.求
的通项公式.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c1d380719b7f8c33f3e3bbce09ccbb91.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19181548bcfbfe7a38a2c84096199563.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf068678969571e78425d6f279cd1995.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
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【推荐2】设
是公差大于0的等差数列.其前
项和为
,
且
.
(1)求数列
的通项公式;
(2)若
,求数列
的前
项和
.
![](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/039e4fe671d61e59b96ee525c9df43e8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b52e18f280e65998d2ee45f6a7a43b18.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/18ec386f0f3ddad65efa9fac2d5bc5d0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
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名校
【推荐1】已知数列
满足![](https://staticzujuan.xkw.com/quesimg/Upload/formula/925f52e9e8f9143a737f9d9edfc72325.png)
(1)求证:
为等比数列;
(2)求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/925f52e9e8f9143a737f9d9edfc72325.png)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e2de706dc5f0439b989273a5367f63a.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/831ed34d8c6d99fdd0b94688ef03bfcb.png)
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【推荐2】等比数列
中,
,
.
(1)求
的通项公式:
(2)记
为
的前n项和,若
,求m.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76aef4cdcb5af742ce28003b7b6c8c20.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b065334d8f60c49f4bd3d9f1373fe4cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7af2c1210720d61e5d57d1564d1e0d8f.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76aef4cdcb5af742ce28003b7b6c8c20.png)
(2)记
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76aef4cdcb5af742ce28003b7b6c8c20.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fac26e75b047caf53e9d14db0ffe8e48.png)
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