在等差数列
中,
,求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76aef4cdcb5af742ce28003b7b6c8c20.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/35ce9f8d5cd8c2ea34d86b7beb82ff31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2491a90305e289d2414f1ab786b8c563.png)
更新时间:2017-11-12 19:10:51
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【知识点】 求等差数列前n项和
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解答题-问答题
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【推荐1】在等差数列{an}中,已知a1+a3=12,a2+a4=18,n∈N*.
(1)求数列{an}的通项公式;
(2)求a3+a6+a9+…+a3n.
(1)求数列{an}的通项公式;
(2)求a3+a6+a9+…+a3n.
您最近一年使用:0次
【推荐2】记
为等差数列
的前
项和,已知
,
.
(1)求
的通项公式;
(2)求
.
![](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/bbe7bdaaf8b0adf10bf2ef6c1255b1dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a9875b5a21e007035dbf079af4617d3b.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
您最近一年使用:0次