已知数列{ an }的前n项和为sn,a1=1,sn+1=sn+an+6求数列{ an }的同项

题目

已知数列{ an }的前n项和为sn,a1=1,sn+1=sn+an+6求数列{ an }的同项
请讲解这一步s(n+1) = sn + a(n+1) = sn+an+6,a(n+1) = an + 6

答案

a1=1
s1=1
s(n+1) = sn + a(n+1) = sn+an+6, a(n+1) = an + 6
是个等差数列
an = 1 +6*(n-1) = 6n - 5