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问题: 已知正数列{an}满足,Sn=2an-1,求{an}的通项公式.

已知正数列{an}满足,Sn=2an-1,求{an}的通项公式.

解答:

Sn =2*An -1, A1=1
S(n-1) =2*A(n-1) -1
==> An =Sn -S(n-1) =2*An -2*A(n-1)
An/A(n-1) =2
==> An =2^(n-1)