1 . 已知
,等比数列
,
,
,…,的第4项为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58b140e221ddf537b8964fff8557cca0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f2c1ec3153d6b86778f01cb90027029.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2360f4c62f7f1173922e755529a00fae.png)
A.12 | B.![]() | C.9 | D.![]() |
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2 . 已知数列
是公比大于0的等比数列.其前
项和为
.若
.
(1)求数列
前
项和
;
(2)设
,
.
(ⅰ)当
时,求证:
;
(ⅱ)求
.
![](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/6ff14226c25417181e3daab4b157096f.png)
(1)求数列
![](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)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a2a471526dab88625f06b7708cd7b991.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c73e4aa3454443728cd5e6e24d9f839c.png)
(ⅰ)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca4bfbc02ee7a09136dd3c0db55c8a6c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/268a83236c72c04376c3686016a309c5.png)
(ⅱ)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbe5f87926e73c8c0fa2df903a964bb7.png)
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名校
3 . 已知
是等比数列,
是其前n项和,
,下列说法中正确的是( ).
![](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/48bf2138c305e7d3ab3c2999eec10c60.png)
A.若![]() ![]() |
B.![]() ![]() ![]() |
C.若存在![]() ![]() ![]() ![]() |
D.若对任意![]() ![]() ![]() ![]() |
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名校
4 . 已知递增数列
和
分别为等差数列和等比数列,且
,
,
,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2fceda903b8403b0b46ba9bbc95aa74.png)
(1)求数列
和
的通项公式;
(2)若
,证明:
.
![](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/4f86f99671fe8a18caba3f5393042e2e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fe1d9e4be779bb43c2b4e1492be3089.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7b422ea651a522bb576e69e4a98673c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2fceda903b8403b0b46ba9bbc95aa74.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f990fd9ddc8e2133738921d8c0fa755.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29fe76cada9145bb9654d2ad1b11d028.png)
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5 . 已知等差数列
的前
项和为
,且
,
,若将
去掉一项后,剩下三项依次为等比数列
的前三项,则
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/81911c0e1a8b5472bbec7b78974f5bf2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d55f82fc5641af25aaf2533015d4273e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ed6fe44bc49b478979589face327799.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a548938d87c80ac47910607d3857007f.png)
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6 . 已知数列
为等比数列,
,
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3bb7147e313f9d9f67d19ecb5f499c05.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/259b2e755105c0ee479eabf7265a76a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2f236846ca02c90b7633fda2d1a9a82.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3bb7147e313f9d9f67d19ecb5f499c05.png)
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7 . 在正项等比数列
中,
,则数列
的公比为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b75b181ed9f78a0ed14ba951d400689.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
A.![]() | B.4 | C.![]() | D.2 |
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解题方法
8 . 记正项等比数列
、等差数列
的前
项和分别为
,已知
,
.
(1)求
和
的通项公式;
(2)设集合
,求
中元素的个数.
![](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/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/478421b81927e435cbcf5acafa89efd7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6bccd2aaf87a4a0c57a111c92bb88087.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f68e340c43602bb6d26a74a1fbd2dea2.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
(2)设集合
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/909d158831ad898afbad9278cf3dcdf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
您最近一年使用:0次
解题方法
9 . 已知数列
是等差数列,满足
,
,数列
是公比为
的等比数列,且
.
(1)求数列
和
的通项公式;
(2)求数列
的前
项和
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d1928c254cfada1f75a5cd1e34db5a63.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5fce21bf93e1492b6d657a851d189e1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39850521e5f5220161b0d3f5dc6543b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/385275d29d8c8a7841eaeaa3dfab2cdb.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/08eb71ecf8d733b6932f4680874dbbf3.png)
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解题方法
10 . 已知数列
中,
,
(
,
),且
是
和
的等差中项.
(1)求实数
的值;
(2)求证:数列
是等比数列,并求出
的通项公式.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76aef4cdcb5af742ce28003b7b6c8c20.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b13a6e1d671215fc96e4bee3541d1096.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf7dfbcf6abb1df938b24074cd048683.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76d8047f0a8bd0cf4e250cd0fe80093b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80c873cf33f90999dca0e29fe113db34.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58b3175ab6772cd611f9c42771a9467d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e72adb45c60c2f63b46e65ff787302bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dda6c54eafc6fe26d710ff3d8cb7b5a6.png)
(1)求实数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
(2)求证:数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82f8b6edfb7d680d88ed991d5c552c43.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76aef4cdcb5af742ce28003b7b6c8c20.png)
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