Question

已知等差数列{an},a6=5,a3+a8=5,（1）求{an}的通项公式an,（2）若数列满足bn=A2n－1,求{b

Answer 1

a1+5d=5,

a1+2d+a1+7d=5

∴a1=-20,d=5

∴an=a1+(n-1)d=5n-25

bn=a(2n-1)=5(2n-1)-25=10n-50