设数列{an}的前n项和是Sn,Sn满足：S1=a(a≠0),Sn+1 =3Sn+1(n∈N*),数列{bn}满足：bn+2 =2bn+1-bn,且

题目

设数列{an}的前n项和是Sn,Sn满足：S1=a(a≠0),Sn+1 =3Sn+1(n∈N*),数列{bn}满足：bn+2 =2bn+1-bn,且
设数列{a­n}的前n项和是Sn,Sn满足：S1=a(a≠0),Sn+1 =3 Sn+1(n∈N*),数列{bn}满足：bn+2 =2bn+1-bn (n∈N*),且b3=3,b5=9.
(1)分别求数列{a­n}和{bn}的通项公式；
(2)若a=1,若对任意的n∈N*,都有(Sn+1/2)*k≥bn恒成立,求实数k的取值范围.

答案