设数列{an}是等差数列数列,{bn}是各项都为正数的等比数列,且a1=b1=1,b1+b2=a2,b3是a1与a4的等差中项

∵{an}是等差数列数列,{bn}是各项都为正数的等比数列∴b1+b2=a2∵a1=b1=1即1+q=1+d ∴q=d又∵2b3=a1+a4 ∴2q²=2+3d结合q=d得q=2或q=-1/2∵bn各项均为正数∴q=-1/2(舍去) q=d=2∴an=1+2(n-1)=2n-1bn=2^(n-1)令Tn...