- #1

rajeshmarndi

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## Homework Statement

The combination of n different object, taken r at a time(repeatation allowed) is given by

C

^{n}

_{r}= (n-1+r)! / [(n-1)! r!]

## Homework Equations

## The Attempt at a Solution

The above formula is deducted, as it is same as no. of ways of placing n-1 bar in n-1+r places, which is same as combination (repeatation not allowed) of n-1 object placed in n-1+r places. But permutation and combination formula or online calculator doesn't allow when r>n, (r= place, n= no. of objects). Then how is the prove of the above formula deducted?

Also the above formula is similar to combination(repeatation not allowed) of n-1+r object placed in r places.