| 1 | 1 | 1 | 1 | |||||
∑∞n=1 | =∑( | − | + | )= | ||||
| n(n+1)(n+2) | 2n | n+1 | 2n+2 |
| 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | ||||||||||
− | + | + | − | + | + | − | + | + | +...= | ||||||||||
| 2 | 2 | 4 | 4 | 3 | 6 | 6 | 4 | 8 | 8 |
| 1 | 1 | 1 | 1 | ||||
− | + | − | |||||
| 2 | 3 | 3 | 4 |
| 1 | 1 | |||
+ | +...= | |||
| 4 | 2 |
| 1 | 1 | 1 | 1 | ||||
= | − | + | = | ||||
| n*(n+1)*(n+2) | 2n | n+1 | 2*(n+2) |
| 1 | 1 | 2 | 1 | |||||
= | *( | − | + | )= | ||||
| 2 | n | n+1 | n+2 |
| 1 | 1 | 1 | 1 | 1 | ||||||
= | *[( | − | )−( | − | )]= | |||||
| 2 | n | n+1 | n+1 | n+2 |
| 1 | ||
S= | ||
| 4 |