Combination

Combination

• Nb of ways to choose $K$ out of $N$ distinct objects, order don’t matter $\to$ set of ways $C(N,K)=(\genfrac{}{}{0ex}{}{N}{K})$ ^f4f5ad
  • ${}_N{\text{C}}_K=\left(\genfrac{}{}{0ex}{}{N}{K}\right)=P(N,K)/K!=\frac{N!}{K!(N-K)!}$