C (m+n , r) = C(n,0) *C(m , r) + C(n , 1) * C(m, r-1) + ...... + C(n , r) * C(m , 0) give combinatorial argument for it. (I did not write the parantez
C(n , k) = C(k-1 , k-1) + C(k , k-1) + ........ + C(n-1 , k-1) give combinatorial argument for it. (I did not write the parantez
C(n , k) = C(k-1 , k-1) + C(k , k-1) + ........ + C(n-1 , k-1) give combinatorial argument for it. (I did not write the parantez