OB |
OA |
OA |
OB |
0 |
OA |
OB |
OC |
0 |
OA |
OB |
OC |
0 |
OA |
OB |
OC |
OD |
0 |
OA |
OB |
OC |
OD |
0 |
A.连续两项的和相等的数列叫等和数列 |
B.从第一项起,以后每一项与前一项的和都相等的数列叫等和数列 |
C.从第二项起,以后每一项与前一项的差都不相等的数列叫等和数列 |
D.从第二项起,以后每一项与前一项的和都相等的数列叫等和数列 |
a1 |
1 |
a2 |
2 |
a3 |
3 |
a4 |
4 |
4 |
i=1 |
2S |
k |
S1 |
1 |
S2 |
2 |
S3 |
3 |
S4 |
4 |
4 |
i=1 |
A.
| B.
| C.
| D.
|
n |
n |
1 |
n |
π |
2 |
π |
2 |
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