Example 1:
In a conference of 9 schools, how many intraconference
football games
are played during the season if the teams all play each other exactly
once?
Solution:
If n is the number of teams
we have to choose from, then n = 9
because there are 9 teams in the conference.
To continue on, please click on the Next button.
If r is the number of teams
we are using at a time, then r = 2 because
2 teams play per game.
n = 9, r = 2
evaluate inside ( )
expand 9! until it gets to 7!
cancel out the 7!'s
