an+an+2 |
2 |
bn+bn+2 |
2 |
5n-2n+5(n+2)-2n+2 |
2 |
5 |
4 |
5 |
4 |
bn+bn+2 |
2 |
n(n+1) |
2 |
sn+sn+2 |
2 |
-n2+9n-(n+1)2+9(n+2) |
2 |
sn+sn+2 |
2 |
9 |
2 |
81 |
4 |
OB |
OA |
OC |
A.2009 | B.
| C.22009 | D.2-2009 |
A.
| B.12 | C.6 | D.
|
A.S10<0 | B.S5<S6 | C.S5>S6 | D.S5=S6 |
a5 |
a3 |
A.6 | B.7 | C.8 | D.9 |
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