S2009 |
2009 |
S2007 |
2007 |
A.-2008 | B.2008 | C.-2010 | D.2010 |
n(n-1)d |
2 |
Sn |
n |
(n-1)d |
2 |
S2009 |
2009 |
S2007 |
2007 |
(2009-1)d |
2 |
(2007-1)d |
2 |
S2010 |
2010 |
(2010-1)d |
2 |
A.公差为-1的等差数列 | B.公差为5的等差数列 |
C.首项为5的等差数列 | D.公差为n的等差数列 |
A.a1+a101>0 | B.a2+a102<0 | C.a3+a99=0 | D.a51=51 |
A.{an}递增,Sn有最大值 | B.{an}递增,Sn有最小值 |
C.{an}递减,Sn有最大值 | D.{an}递减,Sn有最小值 |
1 |
3 |
A.是递增的等比数列 | B.是递减的等比数列 |
C.是递增的等差数列 | D.是递减的等差数列 |
1 |
2 |
A.1 | B.2 | C.3 | D.4 |
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