Review Material -- Exponents

I just started Pre-Calc last week and am already stuck. I added the course late (college freshman) and consequently missed three classes. Those three classes were, apparently, focused on reviewing College Algebra.

Now, I liked Algebra, I did. I did really well in it too but I haven't had it in four or five years. As a result, I've forgotten a lot of what I once knew. Unfortunately, the professor did a lot of the work in class but because I wasn't there, I have to get the answers myself.

If someone could help me, I should be fine. I just need some reminders. (Nod)

(a^2/b^3)^-2

x^2y^-4/x^-5y^-2

[(x/y)^-2]^3

All of the exponents are to be positive.

I *think* I can do the rest of the review packet on my own. (Rofl)