已知点
是函数
的图象上一点,等比数列
的前n项和为
,数列
的首项为c,且前n项和
满足:当
时,都有
.
(1)求c的值;
(2)求证:
为等差数列,并求出
.
(3)若数列
前n项和为
,是否存在实数m,使得对于任意的
都有
,若存在,求出m的取值范围,若不存在,说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6c7d1e7ffa7d5bfb2aa3c333536a8a9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2bb2fb6043949ffd4a0fc14967e23c90.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf709bf820e5dfd72cf126941d23a6f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dad559edf20866cca8aa782a0a72e14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0704f453b2de48d36911f7db496bbf82.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/51a91d71e4955e783a6dcec4b20f1328.png)
(1)求c的值;
(2)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c117df5d7d4e489f7b9b763d187792c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/686ece75006ad358f23314dc8a246e11.png)
(3)若数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5da72309d2507e2f5e5ed88d8cc08963.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e145b6046bc80d0ffecc61ac67c87ca1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a8a65af0ed8684edc5c6489ff1d263e.png)
更新时间:2020-02-11 13:28:24
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