1 |
2 |
1 |
2-an |
1 |
an-1 |
1 |
an+1-1 |
1 |
an-1 |
1 | ||
|
1 |
an-1 |
2-an |
-1+an |
1 |
an-1 |
-an+1 |
an-1 |
1 |
a1-1 |
1 |
an-1 |
1 |
an-1 |
n |
n+1 |
n+1 |
n+2 |
n |
n+1 |
(n2+2n+1)-(n2+2n) |
(n+2)(n+1) |
1 |
(n+2)(n+1) |
A.
| B.
| C.
| D.
|
1 |
4 |
1 |
a |
1 |
b |
1 |
c |
A.a1=-2,d=3 | B.a1=2,d=-3 | C.a1=-3,d=2 | D.a1=3,d=-2 |
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