已知公比为正数的等比数列
满足
,
,
,
,成等差数列.
(1)求
;
(2)若
,求
的前2n项的和.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0326cf308e9b42abf9e94fa55fd559e1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f9d2e152db0845ff23e4ea0cd00974d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/daf464629fa321a6ff7401ab79f07083.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67e217c18cac93caa9e78468f0a99965.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f3d1b9c8102ebd8eecc63b92ac32f376.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
2021·河南·模拟预测 查看更多[2]
更新时间:2022-02-26 19:53:42
|
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解答题-问答题
|
适中
(0.65)
解题方法
【推荐1】已知
是各项均为正数的等差数列,
、
、
成等差数列,又
,
,
,
……证明:
为等比数列.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d454255d882c4d20e97d8de506473b6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7e22668dff7ccd42fbe20af43eb26f74.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ca7d1107389675d32b56ec097464c14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
解题方法
【推荐2】在
中,内角A,B,C所对应的边分别为a,b,c.
(1)若
,
,求角A的值;
(2)若
,且b是a和
的等差中项,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f37bbd6940063ebe81e02f41d34c86cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eebf70d9224a4c8d150acb0619e1750a.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e899c486dc49e560fc4aca05e16835b7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4f26ae0e31513d85924fd32aca9b9a0c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4e563e032dfdef69b0f357060c27bd4.png)
您最近一年使用:0次
解答题-问答题
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适中
(0.65)
解题方法
【推荐1】已知数列
是首项为
,公差
的等差数列,且它的第2、3、6项依次构成等比数列
的前3项.
(1)求
的通项公式;
(2)若
,求数列
的前项和
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acbc6a613224461ade69362d46550474.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/812be9806122241c476ba1db516c4823.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b9221c0c92a526f65533cdc5400767af.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
解答题-问答题
|
适中
(0.65)
解题方法
【推荐2】已知数列
的各项均为正数,记
为
的前
项和,___________.从下面①②两个条件中任选一个,补充在上面的题目中,再解答下列问题.
①
是等比数列且
,
;②
.
(1)求数列
的通项公式;
(2)设
,记
为
的前
项和,证明:
.
![](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/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22fdcaf78e41a30864cfe42ebce79301.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a316124e688e76d6f330ffbea49d427d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c8370a173854471a3eb27637993a3d5d.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a30a4fb34ebc5f59e6586fa1fa0a6e99.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.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/08299124b1d23c57a0fb290e0564b34b.png)
您最近一年使用:0次
【推荐1】已知
为等差数列,公差
中的部分项
恰为等比数列,且公比为
,若
;
(1)求
;
(2)求数列
的通项公式及其前
项之和.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76aef4cdcb5af742ce28003b7b6c8c20.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97c735c0e81a29cd3ec7d96d1e895c25.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1cd7d8dd0ad47b893f16c3df9f961212.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9aa8a716a31b0f51b70fdf9bdb257909.png)
(2)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/089371cf5f29c549977e2f4b8dd8b8ea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
您最近一年使用:0次
【推荐2】在数列
中,
.设
,求数列
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f224ea87a12e41e153de9760a14bb24.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
您最近一年使用:0次