Algebra and Trigonometry, 5th Edition

11.5 Combinatorics: Permutations

• Evaluate factorial notation and permutation notation and solve related applied problems.

In order to study probability, it is first necessary that we learn about combinatorics, the theory of counting.

Permutations

In this section, we will consider the part of combinatorics called permutations.

The study of permutations involves order and arrangements.

Example 1

How many 3-letter code symbols can be formed with the letters A, B, C without repetition (that is, using each letter only once)?

Solution

Consider placing the letters in these boxes.

We can select any of the 3 letters for the first letter in the ...