已知等比数列{an}的公比为q,前n项和为Sn,若S2011,S2010,S2012成等差数列,且S1=1,则an等于

已知等比数列{an}的公比为q,前n项和为Sn,若S2011,S2010,S2012成等差数列,且S1=1,则an等于
已知等比数列{an}的公比为q,前n项和为Sn,若S2011,S2010,S2012成等差数列,且S1=1,则an等于

已知等比数列{an}的公比为q,前n项和为Sn,若S2011,S2010,S2012成等差数列,且S1=1,则an等于
由{an}为等比数列,设公比为q,易知
a2012=q·a2011
即 S2012-S2011=q(S2011-S2010)
又 S2011,S2010,S2012成等差数列
∴ S2012-s2011=S2011-S2010
∴ q=1
∵S1=1
∴a1=1
∴an=1