已知数列{an}满足a1=1,an>0,Sn是数列{an}的前n项和,对任意的n∈N*,有2Sn=2an2+an-1.(1)求数列{an

2025-04-29 03:26:30
推荐回答(1个)
回答1:

(1)由2Sn=2an2+an-1,得2Sn+1=2an+12+an+1?1
两式相减得:2an+1=2(an+1-an)(an+1+an)+(an+1-an)?
(an+1+an)(2an+1-2an-1)=0
∵an>0,∴2an+1-2an-1=0,∴an+1an+

1
2

∴数列{an}是以1为首项,
1
2
为公差的等差数列
an
n+1
2

( 2 )由bn
an
2n
=
n+1
2n+1

Tn
2
22
+
3
23
+
4
24
+…+
n+1
2n+1
,①

1
2
Tn=
2
23
+
3
24
+
4
25
+…+
n+1
2n+2
.②

①-②得:
1
2
Tn
=
2
22
+
1
23
+
1
24
+
1
25
+…+
1
2n+1
?
n+1
2n+2

=