Sn+64 |
an |
A.7 | B.
| C.8 | D.
|
n(n-1) |
2 |
Sn+64 |
an |
n2+n+64 |
2n |
1 |
2 |
64 |
n |
1 |
2 |
n•
|
17 |
2 |
A.3 | B.5 | C.7 | D.9 |
A.0 | B.2 | C.2009 | D.4018 |
A.②③ | B.①③ | C.①④ | D.②④ |
A.S9<S10 | B.S9=S10 | C.S11<S10 | D.S11=S10 |
A.d<0 | B.a7=0 |
C.S9>S5 | D.S6与S7均为Sn的最大值 |
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