Your algebra is good- it's yourcountingyou need to work on! You don't have "four" and "three" factors.

As I believe I told you on a different forum, think of as and factor as the "difference of two squares", . Since those are both odd powers, each will factor as you have above.

Think of as . Again, you can factor that as the "difference of two square": . Now, you can factor again but since you have an even power now, you cannot factor [tex]x^2+y^2[tex] further.