# Symmetry Group of Polynomials

1. Sep 4, 2009

### polarbears

1. The problem statement, all variables and given/known data
$$(x_1 - x_2)(x_3 - x_4)$$
Find permutations of subscripts that leave value unchanged

2. Relevant equations

3. The attempt at a solution
Okay so I know that it's asking how I should rearrange things and still not change the value.
Switching 1 with 2 or 3 with 4 would work but I know there's more than that but I'm don't know how to show it.
I guess I can expand it but I'm not sure if that helps

2. Sep 4, 2009

### Dick

"Switching 1 with 2 OR 3 with 4" doesn't work, "switching 1 with 2 AND 3 with 4" does. How about switching 1 with 3 and 2 with 4? Hmm?