网址:http://m.1010jiajiao.com/timu3_id_4472701[举报]
等比数列的前n项和为,且4,2,成等差数列。若=1,则=( )
A.16 B.15 C.8 D.7
等比数列的前n项和为,且4,2,成等差数列。若=1,则="( " )
等比数列的前n项和为,且4,2,成等差数列。若=1,则=
A.7 B.8 C.15 D.16