S415的知识精选

设等比数列{an}的前n项和为Sn.若S2=3,S4=15,则S6=()A.31               ...
问题详情:设等比数列{an}的前n项和为Sn.若S2=3,S4=15,则S6=()A.31                        B.32                         C.63                     ...
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