在等差数列
中,已知
.在①
,②
,③
这三个条件中任选一个补充在第(2)问中,并对其求解.
(1)求数列
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/3cf07eb6556fe62bccf3ec869e6a78c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d289d8e284958dbe5e78494e37f3149.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a9be5bf50c5db10bdfef370807b0104d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/631f98c11ef576c27795bfe45c97029b.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
(2)若___________,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)
更新时间:2020-07-05 16:51:07
|
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