解题方法
1 . 各项为正数的数列
如果满足:存在实数
,对任意正整数n,
恒成立,且存在正整数n,使得
或
成立,则称数列
为“紧密数列”,k称为“紧密数列”
的“紧密度”.已知数列
的各项为正数,前n项和为
,且对任意正整数n,
(A,B,C为常数)恒成立.
(1)当
,
,
时,
①求数列
的通项公式;
②证明数列
是“紧密度”为3的“紧密数列”;
(2)当
时,已知数列
和数列
都为“紧密数列”,“紧密度”分别为
,
,且
,
,求实数B的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2397df3279607612ea3cbef101ee0bf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc9dd0fff52e661d24556933e0b2fb13.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dcbb3965c6d873ee274a572f7b28f544.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b91d28481ee7422fe0d91669dce697a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](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/2b0b5f7c8a883316d64855f17e71942c.png)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/62e4de71feae82210ab5a2f5627002bd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f60c30cc5b059aac0e6fa6dd3a5dc943.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac88e202c8f32621171f010ccfceba67.png)
①求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
②证明数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/601a4fe4960f18539e153430f5078b69.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/846fa57d92d6ad44d6a0cafad1e71ed4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6defc43285a40f7ccb74c1cc04265eba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/423b7ae39db552e60ee8b1d27312306f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6defc43285a40f7ccb74c1cc04265eba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9049dd395a386fe8e30320f3f2abd28f.png)
您最近一年使用:0次
2 . 若各项均为正数的数列
满足
(
为常数),则称
为“比差等数列”.已知
为“比差等数列”,且
.
(1)求
的通项公式;
(2)设
,求数列
的前
项和
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5ab0309e2cd35585ea9fb2cc3017abf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c36015c4b91a1135a2ff74703223ef5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0879d99ab58ff2e7e0f7de85a22b3927.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5ab0309e2cd35585ea9fb2cc3017abf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76aef4cdcb5af742ce28003b7b6c8c20.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/859d71bfaa83e09f4da1bc1dbc2fe296.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76aef4cdcb5af742ce28003b7b6c8c20.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8da64b8fbf8f7c06beedc50d38fbf505.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f329b217e1051b23f0d61023cdc6e69.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
您最近一年使用:0次
2024-06-13更新
|
89次组卷
|
2卷引用:2024届湖南省长沙市第一中学高考最后一卷数学试题
3 . 设数列
的前
项和为
,
,
,若
,则正整数
的值为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76aef4cdcb5af742ce28003b7b6c8c20.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/0ea8d0e50065114b05ef2dc1ea1129cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c840b24a1626f247eefe7371c8abb50e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f16c5c6c416370c28c70dfb9fe1d769f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
A.2024 | B.2023 | C.2022 | D.2021 |
您最近一年使用:0次
4 . 已知数列
的奇数项是首项为1的等差数列,偶数项是首项为2的等比数列.设数列
的前n项和为
且满足![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53877766161e237e871b298b38ac0128.png)
(1)求数列
的通项公式;
(2)若
求正整数
的值;
(3)是否存在正整数
,使得
恰好为数列
的一项?若存在,求出所有满足条件的正整数
;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d7a9511c3d1b6d41d17df1559919880.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53877766161e237e871b298b38ac0128.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c90616641d2f2cf0e5d533fc4813c6cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
(3)是否存在正整数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d447e1dc2898e19f4be02b41086d09d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
您最近一年使用:0次
2020-02-02更新
|
247次组卷
|
2卷引用:2016届上海市虹口区高三4月高考练习(二模)(文)数学试题
5 . 记数列
的前
项和为
,已知数列
满足
.
(1)若数列
为等比数列,求
的值;
(2)证明:
.
![](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/7ee01c02a6d9f1607ddd0a67321117e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0325d1b55febf42799fef88313e6a7a9.png)
(1)若数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ea7c3a97a4f315982893f15331fff80.png)
(2)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85460d2be5018509de4ab2420b83e133.png)
您最近一年使用:0次
名校
6 . 设
为数列
的前
项和,
,且
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5e4c5f2eabcfbcb67eeec6e4ca96fa58.png)
_ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1e856be82991b12503a77adc3c43eab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f3591a6fa3bbc87b646967ff838369d8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5e4c5f2eabcfbcb67eeec6e4ca96fa58.png)
您最近一年使用:0次
2017-12-07更新
|
745次组卷
|
5卷引用:山西省榆社中学2018届高三11月月考数学(文)试题
7 . 已知函数
的定义域为实数集
,及整数
、
;
(1)若函数
,证明
;
(2)若
,且
(其中
为正的常数),试证明:函数
为周期函数;
(3)若
,且当
时,
,记
,求使得
小于1000都成立的最大整数
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b68df477b3ee45ac0f725db00d465a1.png)
(1)若函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd51682d8c1d1e3026491f80fe42a62f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5902f82f85151a94fe0969316c425bc8.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4e37bbc29ff4f1ac790aedbc574e862.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cfca1a1d2e308d840e267d9018f88f01.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/544f91d4fb22c571db9f8481b72a0419.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/606c24b88c4453aa408f952c457eac6c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5850426712b921e7c18b9a9a43712cc0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69fff4254c13c9170673d8f1b6e1a022.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9afb7f58145b5dd42a239ede573720c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d595196ae6d52febfe4b499838e35b4a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
您最近一年使用:0次
2020-02-01更新
|
235次组卷
|
2卷引用:上海市八校2016届高三下学期3月联考(理)数学试题
8 . 已知数列
满足
,且
.
求证:
;
令
,且
,试求无穷数列
所有项的和;
对于
,求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a28f8526a5b45689a277af76d37fb5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4636f7f783fbc9e2da112efa7919f579.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9bf6c84731e5e1bd335ecfc2d36c3d81.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d784b3a582342a9a36b14546fa560552.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f53190d6ead827a6338b9de847aeaf1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c9254c203b71de0bf8e07f8506f4a7bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8bd9c1ef5d4d6fbe958c8eb4ff6c1817.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e30136113176ba7fe660e998d0873157.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f62295c36d2e2174908c2bec0eb5b30f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/576ea0f23e66276d14e99a90c149c0dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ba9afa028198b58e6ea6f54c4ccdb8a.png)
您最近一年使用:0次
解题方法
9 . 设数列
的前n项和为
,且![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e36b29a7ef6847093a532eac4583538.png)
,
(1)求
、
、
的值,并求出
及数列
的通项公式;
(2)设
求数列
的前n项和![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5eded65284816fdf6bf335b0c2a78e6a.png)
(3)设![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76f9734ff47b8cb7648e4352b8d5b2a8.png)
在数列
中取出
(
为常数)项,按照原来的顺序排成一列,构成等比数列
.若对任意的数列
,均有
试求
的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e36b29a7ef6847093a532eac4583538.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c9fc82353331abee0828dee9b38c08f2.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e097c8d4c948de063796bd19f85b3a9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e0bd63f55069a3bc870915010b39225.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6899bf9cadae2ccdb14cbc87d4f280ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8961a672a9567ed676c73b52cb93fe79.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fce83115a50f99e08e9a2db7267aeed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5eded65284816fdf6bf335b0c2a78e6a.png)
(3)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76f9734ff47b8cb7648e4352b8d5b2a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/28d82e4c2294efbd33e1b268e9a0cec5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38ef4c4439b36c2847b0056a116d56d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe205d289a35590b8f4dde052a9d92d3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d813f3ca8db41a4db6c18eac30fef98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38ef4c4439b36c2847b0056a116d56d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9f29b65f154d161bd8780984c8f8b22.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
您最近一年使用:0次
名校
10 . 已知数列
的前
项和
满足:
(
为常数,且
,
).
(1)求
的通项公式;
(2)设
,若数列
为等比数列,求
的值;
(3)在满足条件(2)的情形下,设
,数列
的前
项和为
,若不等式
对任意的
恒成立,求实数
的取值范围.
![](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/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95a966ff380354a3ee8a35c9c2618161.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/960728f9d01988e099c3cff6bab076e7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/301dd9f9a4fa231560c8bd67b6e5b775.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c252bf4d0af9a612f6649a643d9c0ca3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43b7e7cd571c8cd141cbbfe5d0890bf6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
(3)在满足条件(2)的情形下,设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d1e1f73432895c2807ee3d829c7ca30.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c88a7ef007c78a93e33bd77c4396626.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95ddbae2be6b01707ffa355089d59c63.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5235e9027fd05f69f760241e8f08a13c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
您最近一年使用:0次
2016-12-04更新
|
1164次组卷
|
4卷引用:2017届江苏泰州中学高三摸底考试数学试卷