1 . 已知等差数列
的公差为
,前n项和为
,现给出下列三个条件:①
成等比数列;②
;③
.请你从这三个条件中任选两个解答下列问题.
(1)求数列
的通项公式;
(2)若
,且
,设数列
的前n项和为
,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90bfe21c96489cb30c544d49ddb4c1c8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4f8aa010f7105f3ca426c8a34880abd2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19181548bcfbfe7a38a2c84096199563.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c382dc28bc48eb5a245b1e946489e3a.png)
(1)求数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/176b6b574ad2c11248c2d39d4deaf04d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4995fa0403e013d888c0935ebfe15024.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e30136113176ba7fe660e998d0873157.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1cb91e89800a81f4d62ed75c3ace24a.png)
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2023-04-30更新
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2卷引用:四川省攀枝花市2023届高三第三次统一考试文科数学试题