- #1
Pietjuh
- 76
- 0
Can someone help me how to deal with this identity that i must prove?
[tex]{n + k-1 \choose n - 1} = \sum_{i=1}^k {k-1\choose i -1} {n \choose i}[/tex]
I've tried to figure out what the combinatorial meaning of the right hand side is, but I didn't succeed :(
[tex]{n + k-1 \choose n - 1} = \sum_{i=1}^k {k-1\choose i -1} {n \choose i}[/tex]
I've tried to figure out what the combinatorial meaning of the right hand side is, but I didn't succeed :(