已知数列
的前n项和为
,且n、
、
成等差数列,
.
(1)证明数列
是等比数列,并求数列
的通项公式;
(2)若数列
中去掉数列
的项后余下的项按原顺序组成数列
,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](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/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98851ec1ca2341b0ba5972b20122a112.png)
(1)证明数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e2de706dc5f0439b989273a5367f63a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)若数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57ef6d44448092ebdb9e4a49d866a749.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dca9f124f782685d94f664be0005e61f.png)
2020·陕西西安·一模 查看更多[5]
2020届陕西省西安中学高三第一次模拟考试数学(理)试题黑龙江省大庆实验中学2020-2021学年高三上期中考试数学(理)试题宁夏银川一中2021届高三下学期返校测试数学(理)试题(已下线)专题05 数列 第二讲 数列的求和(解密讲义)(已下线)微专题03 数列中的增项和减项问题
更新时间:2020-04-13 15:00:36
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【推荐1】已知数列{an}的前n项和为Sn,且Sn=n-5an-85,n∈N*.
(1)证明:{an-1}是等比数列;
(2)求数列{an}的通项公式.
(1)证明:{an-1}是等比数列;
(2)求数列{an}的通项公式.
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【推荐2】已知数列
的首项
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.
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b065334d8f60c49f4bd3d9f1373fe4cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f639aa2fde8c717aa78e22e13daab1c4.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a24e6bcf49b8e45531a2d4e4c70c181.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5de771c3bd401cb2f90d24e1c58267e4.png)
(1)求证:数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d363b6982fee3bf1337d1542137a2f3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aec4bdc2a6d4fc387dc621f0b5a268c5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
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解答题-问答题
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适中
(0.65)
【推荐1】已知等比数列
中,
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,
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.
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(2)设
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的前
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9645bd4d2002993b90ec6d48f9c04f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86fc336b4a83bf6d66c4afcc431597f8.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cea4ac187cbb465180e89f38250b3970.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/05eb142564a2e78fa6662d2e30f5047d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fce83115a50f99e08e9a2db7267aeed.png)
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【推荐2】数列
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76aef4cdcb5af742ce28003b7b6c8c20.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/507705d99b3c7907c4ab7e8723c77312.png)
(1)证明:数列
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(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f10ba965988adb22e9b07d89f45017a3.png)
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【推荐1】已知数列{an}的前n项和为Sn,
.
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be2f281fb4eb695e462b8fb0a49a2306.png)
(1)求数列{an}的通项公式;
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f337f8c7ceb49cc82aaf145b87189bc6.png)
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适中
(0.65)
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解题方法
【推荐2】已知数列
的前
项和
,
是等差数列,且
.
(1)求数列
的通项公式;
(2)令
.求数列
的前
项和
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a25ff86d030aefcd645d64e8ccfeae3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43b7e7cd571c8cd141cbbfe5d0890bf6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f3606f02bb1a97dc58645681f81570a.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
(2)令
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6bedee8197910c31adfa2acfe87f20fa.png)
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