在①
,
,
成等差数列;②
,
,
成等差数列;③
中任选一个,补充在下列问题中,并解答.
在各项均为正数等比数列
中,前
项和为
,已知
,且______.
(1)求数列
的通项公式;
(2)数列
的通项公式
,
,求数列
的前
项和
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e88093a749c0d46e0ee931ecfaff925.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c1ccc6c74b8754e9bcbb3f39a11b6f1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ebfa14def8b0176f9f0bcb6d9ceeaa4b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e097c8d4c948de063796bd19f85b3a9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a69480294b121a9800f24ea1e14fe20.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6899bf9cadae2ccdb14cbc87d4f280ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e8c65f76456f36c80e28d926ca03b49.png)
在各项均为正数等比数列
![](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)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77e027201d66112a3b982edb03ba774f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cea4ac187cbb465180e89f38250b3970.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)
19-20高二下·江苏南通·期末 查看更多[6]
江苏省南通市海安高级中学2019-2020学年高二下学期期末数学试题(已下线)专题22数列求和方法的求解策略解题模板(已下线)新高考题型:开放性问题《数列》江苏省南京市第五高级中学2020-2021学年高三上学期9月摸底数学试题(已下线)专题6-2 数列求和15种类型归纳-2022年高考数学毕业班二轮热点题型归纳与变式演练(全国通用)(已下线)专题6-2 数列求和归类-2
更新时间:2020-08-10 00:33:31
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解答题-证明题
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【推荐1】在杨辉三角形中,从第2行开始,除1以外,其它每一个数值是它上面的两个数值之和,该三角形数阵开头几行如图所示.
第0行 1
第1行 1 1
第2行 1 2 1
第3行 1 3 3 1
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第5行 1 5 10 10 5 1
第6行 1 6 15 20 15 6 1
(1)在杨辉三角形中是否存在某一行,使该行中有三个相邻的数之比是3:4:5?若存在,试求出是第几行;若不存在,请说明理由;
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第0行 1
第1行 1 1
第2行 1 2 1
第3行 1 3 3 1
第4行 1 4 6 4 1
第5行 1 5 10 10 5 1
第6行 1 6 15 20 15 6 1
(1)在杨辉三角形中是否存在某一行,使该行中有三个相邻的数之比是3:4:5?若存在,试求出是第几行;若不存在,请说明理由;
(2)已知n,r为正整数,且
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5d3f5a3c16964bc42e8dee1a013b24f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f92a06edab61cd9174b4367d4a0ef007.png)
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【推荐2】已知等差数列
的前
项和为
,且
.
(1)求数列
的通项公式;
(2)若
,求数列
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.
![](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/bbca33843bb50f367b77b6dd443b3911.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f207aed73824768dc75aba2f95b0d6c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
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解题方法
【推荐1】若
.
(1)求证:
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(2)令
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38a1677be1ac78862fad877d7515b3fc.png)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c653177884385ae15b71438aac4e704d.png)
(2)令
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ea8d0e50065114b05ef2dc1ea1129cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ed6fe44bc49b478979589face327799.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
(3)证明:存在不等于零的常数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1010846eeec6c9da29640f5aa3f8738.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fdd8c87dfee13a0ed775d9c256336a6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9aa8a716a31b0f51b70fdf9bdb257909.png)
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【推荐2】已知等比数列
的前n项和为
,
且
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.
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(Ⅱ)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d06eea7ca3541f6590e916ae88f82970.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aec4bdc2a6d4fc387dc621f0b5a268c5.png)
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【推荐1】已知数列
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/472393b18c7880e73b40e31fbe2d951c.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
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【推荐2】已知正项等比数列
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
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