Combinations

A combination is a selection of objects where the order does not matter. It is used when we want to count groups, not arrangements.

Combination Formula

Example: Combination

Properties of Combinations

Example: Using Properties

Permutation and Combination Relationship

Practice Problems

1. Find .
2. If , find .
3. How many ways can a committee of 4 be formed from 8 people?
4. Prove that .