How do I write the problem: How many different arrangements can I have of 2 couples? I know the answer is six. I don't know how to express.

Question

I'm teaching myself linear algebra.  I'm trying to give myself a simple problem regarding combinations and permutations.  If I have two couples (boy/girl for illustration purposes) how can I write the problem so that I can "do the math" instead of brute force?

Answer 1

Obtain a reputable College Algebra or High School Algebra II textbook that addresses Combinatorics, i.e. Permutations, Combinations, Prolbability, etc.

 

If there are four people (2 modern-day 'couples'), then the number of Combinations from four persons taken two at a time is written as 4C2.  By formula, this equals 6:       4! / [2!2!]     In your reading, you will encounter the definition of Factorials.