11111111
所以++…+=1+2+3+…+n=1-n<1. -------12分
22a2-a1a3-a2an+1-an22221. 解:(1)当n≥2时,an?Sn?Sn?1?nan?(n?1)an?1?2(n?1),
得an?an?1?2(n?2,3,4,).
∴数列{an}是以a1?1为首项,2为公差的等差数列.故an?2n?1.-------6分
(2)Tn?11??a1a2a2a3?1111 ????1?33?55?7an?1an?(11?)]2n?12n?1
?1?2n?1??2n?1?
1111111?[(?)?(?)?(?)?2133557n1?1????1??2n?1 ------- 10分
2?2n?1?由Tn?n100得100,满足T?100的最小正整数为12. ------- 12分
?n?n2092n?1209,9n?1?()n,bn?2?3log1()?3n?bn?3n?2 22.解:(1)由已知可得,an?a1q14414n?bn?1?bn?3,?{bn}为等差数列,其中b1?1,d?3. ------- 4分
(2)cn?anbn?(3n?2)()n
Sn?1?1111?4?()2?7?()3????(3n?2)?()n444414 ①
111111Sn?1?()2?4?()3?7?()4????(3n?5)?()n?(3n?2)?()n?1 ② 4444443111111① - ② 得Sn??3[()2?()3?()4????()n]?(3n?2)?()n?1
444444411()2[1?()n?1]114??3?4?(3n?2)()n?11441?4
??Sn?11?(3n?2)?()n?124
212n?81n?1??() . -------8分 33414n(3)cn?(3n?2)?()
11cn?1?cn?(3n?1)?()n?1?(3n?2)?()n4413n?11?()n[?(3n?2)]??9?()n?1(n?1) 444当n?1时,cn?1?cn,当n?2时,cn?1?cn
?(cn)max?c1?c2?若cn?1. 41211m?m?1对一切正整数n恒成立,则m2?m?1?即可 444?m2?4m?5?0,即m??5或m?1. -------12分