设数列{an}的前n项和为Sn,已知a1=1,Sn+1=4an+2 (Ⅰ)设bn
题型:解答题
问题:
设数列{an}的前n项和为Sn,已知a1=1,Sn+1=4an+2
(Ⅰ)设bn=an+1-2an,证明数列{bn}是等比数列
(Ⅱ)求数列{an}的通项公式.
(Ⅲ)设cn=2nbn,求数列{cn}的前n项和Sn.
设数列{an}的前n项和为Sn,已知a1=1,Sn+1=4an+2
(Ⅰ)设bn=an+1-2an,证明数列{bn}是等比数列
(Ⅱ)求数列{an}的通项公式.
(Ⅲ)设cn=2nbn,求数列{cn}的前n项和Sn.