(1)由已知2an-sn-1=0①
当n≥2时,2an-1-sn-1-1=0②(2分)
①-②得2an-2an-1-an=0
整理得
=2an an?1
又n=1时2a1-s1-1=0,得a1=1
∴{an}是首次a1=1,公比q=2的等比数列(5分)
故an=2n-1
(2)由an2=2bn
(2n-1)2=2bn
2n-2=2bn
得bn=2n-2(6分)
则cn=
=bn an
=(2n-2)?(2n?2 2n?1
)n?1(7分)1 2
Tn=c1+c2…+cn-1+cn
=0?(
)0+2?(1 2
)1+…+(2n?4)?(1 2
)n?2+(2n?2)?(1 2
)n?1①1 2
Tn=0?(1 2
)1+2?(1 2
)2+…+(2n?4)?(1 2
)n?1+(2n?2)?(1 2
)n②(10分)1 2
①-②,得
Tn=2?(1 2
)1+2?(1 2
)2+…+2?(1 2
)n?1+(2n?2)?(1 2
)n1 2
=2?
?(2n?2)?(
[1?(1 2
)n?1]1 2 1?
1 2
)n(12分)1 2
解得Tn=4-(2n+2)?(
)n?1.(13分)1 2