| n2−n | ||
1+2+3 + ... + (n−1) = | ||
| n |
| a1 + an | 1 +n−1 | n | n2 | |||||
Ja robię tak : używam wzoru S= | * n = | * n = | *n = | |||||
| 2 | 2 | 2 | 2 |
| n2 − n | n(n − 1) | |||
1 + 2 + 3 + ... (n −1) = | = | = (n − 1) ..bzdura | ||
| n | n |
| n2−n | ||
1+2+3+...+(n−1) = | . − tam w mianowniku jest "2" a nie "n" | |
| 2 |
| n2 − n | ||
ma być: = | .. i teraz udawadniaj | |
| 2 |
| 1 + n | ||
L = | *n − n | |
| 2 |
| n*(n +1) | ||
1 + 2 + 3 + ... + n = | ||
| 2 |
| ( n −1)( n − 1 + 1) | (n −1)*n | n2 − n | ||||
1 + 2 + 3 + ... ( n −1) = | = | = | ||||
| 2 | 2 | 2 |