1.在數(shù)列{an}中,已知an=n+1*(10/11)^n
(1)求n取值范圍,使n為遞減數(shù)列
(2)求數(shù)列{an}的最大值
(3)設(shè)數(shù)列{an}前n項(xiàng)和Sn,求(1/11)S2002
2.已知數(shù)列{Cn},其中Cn=2^n+3^n,且數(shù)列{Cn-1—PCn}為等比數(shù)列
(1)求常數(shù)P
(2)設(shè)數(shù)列{an}{bn}是公比不等的兩個(gè)等比數(shù)列,Cn=an+bn,證明數(shù)列{Cn}不是等比數(shù)列
4.設(shè){an}是公差為d的等差數(shù)列,a3+a5=2 S20=14 有bn=2^a(n)-2a(n+1)
(1)求a1和d
(2)求證{bn}為等比數(shù)列并求bn通項(xiàng)