1 . 设等差数列
的前
项和为
,且
,
.数列
满足
,
,(
,
),
(1)求数列
的通项公式;
(2)设
,求证:
是等比数列,且
的通项公式;
(3)设数列
满足
,求
的前
项和为
.
![](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/18d8e8f821111de8075e5c3dfb22a5d6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd478b1ba0e42545b45d505e2e84a140.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87ea014220aa658c8baa6e1f43e686a2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/739799263dba37badd6e974daea76cd1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac69e6db1df13ed64756b4f391ae9fac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0704f453b2de48d36911f7db496bbf82.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd7aedb05165a366fe03cd5c0f31fcbc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57ef6d44448092ebdb9e4a49d866a749.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
(3)设数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b783cf91e34e692ce8e171f0965cb53f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a47b4789575de0cb8196eb39ad755298.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b783cf91e34e692ce8e171f0965cb53f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
您最近一年使用:0次
名校
2 . 已知从1开始的连续奇数蛇形排列形成宝塔形数表,第一行为1,第二行为3,5,第三行为7,9,11,第四行为13,15,17,19,如图所示,在宝塔形数表中位于第
行,第
列的数记为
,比如
,
,
,若
,则
( )
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/20/ffa4a20c-d6eb-4732-9cb1-fb295d309078.png?resizew=143)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c05b9832b09731a574d4a4adf7448de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7600d2cfbdc6146db96cc545706004f6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4ba1bbe411bc71bca016d3fd82352f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0fbb7397f2a4e7afb7361a13d7b95b5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea718cdbe681628efe6fa588cdb03ece.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/923414bc484033641cdc7266e0499db3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af8cf0265b84100cb03246fcddae324f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4a0ffd97e63546f5181037e416a46aa.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/20/ffa4a20c-d6eb-4732-9cb1-fb295d309078.png?resizew=143)
A.64 | B.65 | C.71 | D.72 |
您最近一年使用:0次
2019-12-27更新
|
559次组卷
|
4卷引用:广东省汕头市金山中学2018-2019学年高三上学期期末数学(理)试题
广东省汕头市金山中学2018-2019学年高三上学期期末数学(理)试题安徽省安庆市怀宁县第二中学2018-2019学年高三上学期第四次月考数学(理)试题(已下线)专题12.1 合情推理与演绎推理 (精练)-2021届高考数学(文)一轮复习学与练(已下线)第二章 推理与证明(能力提升)-2020-2021学年高二数学单元测试定心卷(人教版选修2-2)
名校
解题方法
3 . 已知等差数列
的前
项和为
,且
,数列
的前
项和为
,且对于任意的
,则实数
的取值范围为______ .
![](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/0120550577ea2e8a6a73468692ab2cdc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba57c83d526ac308d1461e80fcca9f36.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/cfe6439a030989579fe4ffddd126182f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
您最近一年使用:0次
2018-01-18更新
|
981次组卷
|
8卷引用:【省级联考】广东省2019届高三上学期期末联考数学理试题
【省级联考】广东省2019届高三上学期期末联考数学理试题河南省中原名校2018届高三上学期第五次联考数学(理)试题河北省定州市定州中学2018届高三上学期期末考试数学试题河北省定州市定州中学2018届高三(承智班)上学期期末考试数学试题(已下线)《2018届优生-百日闯关系列》数学专题四 专题四第五关(已下线)2019年4月21日 《每日一题》文数三轮复习-每周一测(已下线)2019年4月21日 《每日一题》理数三轮复习-每周一测(已下线)专题17 数列(讲义)-1
10-11高三·广东·阶段练习
名校
4 . 已知等差数列
的公差为-1,且
.
(1)求数列
的通项公式
与前n项和
;
(2)若将数列
的前4项抽去其中一项后,剩下三项按原来顺序恰为等比数列
的前3项,记
的前n项和为
.若对任意m,n∈
,都有
恒成立,求实数λ的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d28c990e85d87e43205472a0b0374b3.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
(2)若将数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fce83115a50f99e08e9a2db7267aeed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fce83115a50f99e08e9a2db7267aeed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/52866a74e4af867ceea0efb1ad06602c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f39dda82ddb90816e61b67fd52367fef.png)
您最近一年使用:0次
2020-01-07更新
|
276次组卷
|
15卷引用:2011届广东省执信中学中学高三2月月考数学文卷
(已下线)2011届广东省执信中学中学高三2月月考数学文卷(已下线)2012届浙江省台州中学高三上学期期中考试文科数学试卷2015届湖北省武汉华中师大附中高三5月考试理科数学试卷2016届河北省衡水中学高三上学期四调理科数学试卷2015-2016学年江苏省泰州、靖江中学高一下期中数学试卷重庆市育才中学2014-2015学年高一下学期期中数学(文)试题浙江省绍兴市柯桥中学2019-2020学年高二下学期期中数学试题(已下线)解密03 等差数列与等比数列(分层训练)-【高频考点解密】2021年新高考数学二轮复习讲义+分层训练(已下线)解密03 等差数列与等比数列(讲义)-【高频考点解密】2021年新高考数学二轮复习讲义+分层训练(已下线)专题03等差数列等比数列之测案(文科)第一篇 热点、难点突破篇-《2022年高考文科数学二轮复习讲练测》(全国课标版)(已下线)专题03等差数列等比数列之测案(理科)第一篇 热点、难点突破篇-《2022年高考理科数学二轮复习讲练测》(全国课标版)河南省三门峡市2022-2023学年高三上学期11月月考数学文科试题陕西省渭南市韩城市新蕾中学2021-2022学年高三上学期期中文科数学试题陕西省渭南市韩城市新蕾中学2021-2022学年高三上学期期中理科数学试题河南省三门峡市2022-2023学年高三上学期11月阶段性考试数学(理)试题
2014·广东韶关·一模
5 . 已知
为公差不为零的等差数列,首项
,
的部分项
、
、 、
恰为等比数列,且
,
,
.
(1)求数列
的通项公式
(用
表示);
(2)设数列
的前
项和为
, 求证:
(
是正整数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7fab51121848ce166035ceab6f4e00b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ae8ebcd5b8f8ae04513834a70575816f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e3aaabba90eefb861068bf014f9d0b7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b625d02d9054af978b5fb6ec9bee787.png)
![](https://img.xkw.com/dksih/QBM/2014/4/11/1571616162234368/1571616168067072/STEM/047e3deac63f4153b6b1713b720743b4.png)
![](https://img.xkw.com/dksih/QBM/2014/4/11/1571616162234368/1571616168067072/STEM/725a3eb6fa3e44b1b4476e830bc44c61.png)
![](https://img.xkw.com/dksih/QBM/2014/4/11/1571616162234368/1571616168067072/STEM/e706a003f5114aeea9b30adafbd5235b.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
(2)设数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83fc39b516cab7ca482daa3d507d125d.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/6091ecb815b4a7a94d95593680fc8fc9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
您最近一年使用:0次
解题方法
6 . 已知等差数列
中,
,前
项和为
且满足条件:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/238925337969e24f07793e41455f87f8.png)
(1)求数列
的通项公式;
(2)若数列
的前
项和为
有
,
,又
,求数列
的前
项和
.
![](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/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/238925337969e24f07793e41455f87f8.png)
(1)求数列
![](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/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ea9ddb65d4d2601bd41c69730702b7f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4995fa0403e013d888c0935ebfe15024.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fa0033642afe1efc11e1d2276c21d9df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57ef6d44448092ebdb9e4a49d866a749.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/edd6a506c0a4d15847ac3fc88437908a.png)
您最近一年使用:0次
解题方法
7 . 已知点![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87c6437c5e60fb22c44918407eb5c9d7.png)
在直线
上,
是直线
与
轴的
交点,数列
是公差为
的等差数列.
(1)求数列
,
的通项公式;
(2)求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87c6437c5e60fb22c44918407eb5c9d7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c9fc82353331abee0828dee9b38c08f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/788aa9d4cbc6dbbd5699cc3918098203.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2708fa6298e52f617383efc175b71ddc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
交点,数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
(2)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d329716b489b7e22e1cc20fab873e21.png)
您最近一年使用:0次
名校
解题方法
8 . 设各项均为正数的数列
的前
项和为
,满足
,且
恰好是等比数列
的前三项.
(1)求数列
,
的通项公式;
(2)记数列
的前
项和为
,若对任意的
,
恒成立,求实数
的取值范围.
![](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/280314b6657f239cb1fda1565bc53e79.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3dc54335d4de8adc7c8d5425ba9ee67f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
(2)记数列
![](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)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15a70b95c53fb6655721e2a8c61f5c2c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f712cff19384514c41398f636c00908e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
您最近一年使用:0次
2016-12-04更新
|
449次组卷
|
3卷引用:广东省梅州市兴宁一中2020届高三下学期3月月考数学(理)试题
解题方法
9 . 下表给出的是由n×n(n≥3,n∈N*)个正数排成的n行n列数表,
表示第i行第j列的数,表中第一列的数从上到下依次成等差数列,其公差为d ,表中各行中每一行的数从左到右依次都成等比数列,且所有公比相等,公比为
,若已知![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d124e935b168b9e8427b84c73a660e56.png)
(1)求
的值;
(2)求用
表示
的代数式;
(3)设表中对角线上的数
,
,
,……,
组成一列数列,设Tn=
+
+
+……+
求使不等式
成立的最小正整数n.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/37a14c188b1c9d61aa237b137ba18023.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9aa8a716a31b0f51b70fdf9bdb257909.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d124e935b168b9e8427b84c73a660e56.png)
![]() | ![]() | ![]() | … | ![]() |
![]() | ![]() | ![]() | … | ![]() |
![]() | ![]() | ![]() | … | ![]() |
… | … | … | … | … |
![]() | ![]() | ![]() | … | ![]() |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1349e472ed309807306135794f152a7.png)
(2)求用
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c639c7e5f1e7e7ee5d5ee2f30b155bb0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/37a14c188b1c9d61aa237b137ba18023.png)
(3)设表中对角线上的数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e84c30444f13d37ada78285dc4f83b7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/33e11a5b70e1e2e685d1783a4707872e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f4b25db4e5f4a3743476ae088720fb4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c06519b37bebc4d638da4efa8a6238.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e84c30444f13d37ada78285dc4f83b7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/33e11a5b70e1e2e685d1783a4707872e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f4b25db4e5f4a3743476ae088720fb4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c06519b37bebc4d638da4efa8a6238.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3af0b4987e9b7716b36b5ca99b0db0f2.png)
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2016-11-30更新
|
676次组卷
|
3卷引用:广州省高州一中2009-2010学年高二学科竞赛(数学理)
名校
解题方法
10 . 已知数列
的前
项和为
,若数列
满足:①数列
项数有限为
;②
;③
,则称数列
为“
阶可控摇摆数列”.
(1)若
,请判断数列
是否为“
阶可控摇摆数列”?若是,请求出
的值;若不是,请说明理由;
(2)若等比数列
为“10阶可控摇摆数列”,求
的通项公式;
(3)若等差数列
为“
阶可控摇摆数列”,且
,求数列
的通项公式.
![](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/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ccd4ed75729a7f7a2d5a3d9f7293c53.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/781342df475217b47b622044a112f1d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/353cc14af0e73b3ef2fb65ad1ec07d56.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
(2)若等比数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/917e9c3724f02de6ffd0ed8252ab2166.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(3)若等差数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b84f10b80ce3402ac5369e6a1465d9a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fad491e5b5e14c49ef8b7004ebcfcef9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fa22ba45c62adc96ffe508594edd6900.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
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