When you've got a squares bracket, this simply becomes the bracket twice, therefore, (r+s)2 becomes (r+s)(r+s)
You've then go to use FOIL, and this gives you r^2+rs+sr+s^2, and this cannot be simplified any further.
Therefore, the product of this is r^2 + s^2 + rs + sr
Hope this is what you're looking for :)
