设等比数列{an}的前n项和为Sn,已知S1是S2与S3的等差中项,且a1=3.
(1)求{an}的通项公式;
(2)是否存在正整数n,使得Sn≥2021?若存在,请求出符合条件的所有n的集合,若不存在,请说明理由.
(1)求{an}的通项公式;
(2)是否存在正整数n,使得Sn≥2021?若存在,请求出符合条件的所有n的集合,若不存在,请说明理由.
更新时间:2021-11-06 15:13:05
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【推荐2】设
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(1)求
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解题方法
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