设各项均为正数的数列{an}和{bn}满足5^an,5^bn,5^an+1成等比数列,lgbn,lgan+1,lgbn+1成等差数列,且a1=1,b1=2,a2=3,求通项an,bn猜想:an=n(n+1)/2bn=(n+1)*(n+1)/2假如用数学归纳法做的话当n=k+1时怎么写啊?

问题描述:

设各项均为正数的数列{an}和{bn}满足5^an,5^bn,5^an+1成等比数列,lgbn,lgan+1,lgbn+1成等差数列,且a1=1,b1=2,a2=3,求通项an,bn猜想:an=n(n+1)/2
bn=(n+1)*(n+1)/2假如用数学归纳法做的话当n=k+1时怎么写啊?