ciag geometryczny
rovni: udowodnij
11*2 + 12*3 + 13*4 + ....... + 1n*(n+1) = nn+1
2 lis 13:34
sushi_ gg6397228:
pokaz jak to robisz indukcyjnie
2 lis 13:37
Daromir: Zastosuj wzór:
1n*(n+1)=
1n −
1n+1
Ja bym tego pod geometryczny nie podciągał
2 lis 13:42
Eta:
| | 1 | | 1 | | 1 | | 1 | | 1 | | 1 | | 1 | |
L=(1− |
| ) + ( |
| − |
| ) +( |
| − |
| )+ ..... + ( |
| − |
| )= |
| | 2 | | 2 | | 3 | | 3 | | 4 | | n | | n+1 | |
| | 1 | | 1 | | 1 | | 1 | | 1 | | 1 | | 1 | | 1 | | 1 | |
= 1− |
| + |
| − |
| + |
| − |
| +.... + |
| − |
| + |
| − |
| = |
| | 2 | | 2 | | 3 | | 3 | | 4 | | n−1 | | n | | n | | n+1 | |
| | 1 | | n+1−1 | | n | |
= 1 − |
| = |
| = |
| |
| | n+1 | | n+1 | | n+1 | |
2 lis 13:53