1依题意：3a(n+1)-an-1=0,即：3a(n+1)-(an-1/2)-3/2=0即：3(a(n+1)-1/2)=an-1/2,即：(a(n+1)-1/2)/(an-1/2)=1/3,且a1-1/2=1/6所以：数列{an-1/2}是等比为1/3的等比数列2an-1/2=(a1-1/2)*(1/3)^(n-1)=(1/6)*(1/3)^(n-...