| 1 | ||
∑n k=1 | ||
| (2k−1)(2k+1) |
| 1 | A | B | |||
= | + | = | |||
| (2k − 1)(2k + 1) | 2k − 1 | 2k + 1 |
| A(2k + 1) + B(2k − 1) | (A + B)2k + A − B | |||
= | = | |||
| (2k − 1)(2k + 1) | (2k − 1)(2k + 1) |
| 1 | 1 | |||
A = | ∧ B = − | |||
| 2 | 2 |
| 1 | 1 | |||
∑ | − | |||
| 4k − 2 | 4k + 2 |
| 1 | 1 | ||
− | |||
| 2 | 6 |
| 1 | 1 | ||
− | |||
| 6 | 10 |
| 1 | 1 | ||
− | |||
| 10 | 14 |
| 1 | 1 | ||
− | |||
| 4n − 6 | 4n − 2 |
| 1 | 1 | ||
− | |||
| 4n − 2 | 4n + 2 |
| 1 | 1 | 1 | |||
− | = | ||||
| 2 | 4n + 2 | 2 |