- #1

chaotixmonjuish

- 287

- 0

I'm having problems proving this. However, here is my reasoning:

when factoring out an r you get

[tex]\frac{r*(r-1)!}{(r-k)!k!}[/tex]

[tex]

\frac{r}{r-k}*\frac{(r-1)!}{(r-k-1)!k!}

[/tex]

Is this proper reasoning?

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- Thread starter chaotixmonjuish
- Start date

- #1

chaotixmonjuish

- 287

- 0

I'm having problems proving this. However, here is my reasoning:

when factoring out an r you get

[tex]\frac{r*(r-1)!}{(r-k)!k!}[/tex]

[tex]

\frac{r}{r-k}*\frac{(r-1)!}{(r-k-1)!k!}

[/tex]

Is this proper reasoning?

- #2

Russell Berty

- 107

- 0

I think it should read (r-1)Ck on the right side, not (n-1)Ck.

- #3

chaotixmonjuish

- 287

- 0

Was that an actual proof of the identity?

- #4

Dick

Science Advisor

Homework Helper

- 26,263

- 621

It would be if you write r instead of n in the original statement as Russell Berty pointed out.

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