Question

根据下列条件求数列{an}的通项公式

Answer 1

an=a(n-1)+(1/2)^n

=a(n-2)+(1/2)^(n-1)+(1/2)^n

=...

=a1+(1/2)^2+(1/2)^3+...+(1/2)^n

=2+1-(1/2)^(n-1)=3-(1/2)^(n-1)