Question

数列{an}是公差为1的等差数列.数列{bn}满足b1=1,bn=3an+2

Answer 1

1) bn=3an+2

∴b﹤n-1﹥=3a﹤n-1﹥+2

bn-b﹤n-1﹥=3an+2-(3a﹤n-1﹥+2)=3(an-a﹤n-1﹥)=3*1=3

∴{bn}是以b1=1为首项,d=3为公差的等差数列

2) bn=b1+(n-1)d=1+(n-1)*3=3n-2