a(n+1)=2an-1a(n+1)-1=2(an-1)[a(n+1)-1]/(an-1)=2,为定值.a1-1=3-1=2数列{an}是以2为首项,2为公比的等比数列.an=2×2^(n-1)=2^n数列{an}的通项公式为an=2^nbn=a^(n-1)/[ana(n+1)]=2^(n-1)/[2^n×2^(n+1)]=1/2^(n+2)...