已知数列
的前n项和为
.
(Ⅰ)若
为等差数列,求证:
;
(Ⅱ)若
,求证:
为等差数列.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
(Ⅰ)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f70e63ef83ef4bfd67a54a44ce207889.png)
(Ⅱ)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f70e63ef83ef4bfd67a54a44ce207889.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4be2164a2c67d6163faee87a10942bb.png)
18-19高一下·四川成都·期中 查看更多[4]
【全国百强校】四川省成都外国语学校2018-2019学年高一下学期期中考试理科数学试题四川省成都外国语学校2018-2019学年高一下学期期中考试文科数学试题陕西省汉中市五校2020-2021学年高二上学期第一次月考数学试题(已下线)专题3 等差数列的判断(证明)方法 微点1 定义法、等差中项法
更新时间:2020-10-31 10:29:17
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【推荐1】已知各项均为正数的等比数列
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名校
【推荐1】已知公差大于0的等差数列
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【推荐2】“渐升数”是指每一位数字都比其左边的数字大的正整数(如236),那么三位渐升数有多少个?其中比516大的三位渐升数共有多少个?
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