1 . 已知等差数列
的前
项和为
,
,从条件①、条件②和条件③中选择两个作为已知,并完成解答:
(1)求数列
的通项公式;
(2)设等比数列
满足
,
,求数列
的前
项和
.
条件①:
;条件②:
;条件③:
.
注:如果选择多个条件分别解答,按第一个解答计分.
![](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/cea4ac187cbb465180e89f38250b3970.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)设等比数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a04fcf0a152b19d49cac680b6199c320.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64b5813774a10b78606c431d072041a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5344eadd4711db34e3f935aedd5fb270.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
条件①:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/18d8e8f821111de8075e5c3dfb22a5d6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97034664bd213a31e81b9625f83d0e26.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85f7519e1b1dd927bc634eedafc88820.png)
注:如果选择多个条件分别解答,按第一个解答计分.
您最近一年使用:0次
2021-08-16更新
|
942次组卷
|
3卷引用:北京市延庆区2020-2021学年高二下学期期末考试数学试题
2 . 已知数列
的前
项和
,则
( )
![](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/9ef5ebf3d1b76a25fafd25954010e6c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30eb42578f654fb61e826026d2199751.png)
A.![]() | B.![]() | C.![]() | D.![]() |
您最近一年使用:0次
3 . 设
是公比不为1的等比数列,
,再从条件①、条件②这两个条件中选择一个作为已知,求:
(1)求
的公比;
(2)求数列
的前
项和.
条件①:
为
,
的等差中项;条件②:设数列
的前
项和为
,
.
注:如果选择条件①和条件②分别解答,按第一个解答计分.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6df1038200f2d97a52c716aab6c3bcb6.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
(2)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a3eee3d01633ee2d179e448c5b5f5ecd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
条件①:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e72adb45c60c2f63b46e65ff787302bf.png)
![](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/63d471926f7b27322d90c82b9ce21d3d.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/25b60e89fc4bb1165bb5da32a75652e6.png)
注:如果选择条件①和条件②分别解答,按第一个解答计分.
您最近一年使用:0次