A Few College Level Math Questions...

I took this entry test so I could dual enroll at a college a few days ago and completely failed the college math part... Since then I've been trying to remember/learn as much as I can so I can go back and pass it... Anyway, I've been looking at sample questions similar to what I'd be going back and doing and I need help understanding the answers to a bunch of them.

Here they are:

2^5/2 - 2^3/2 = 2^3/2

That is what the answer was at least. How is this possible?

Stupid question... Are f(-x) and f^-1(x) the same thing? (inverse operation?)

The equation x2 – 2√2 x + 3 = 0 has as its roots... Answer is √2 + i, √2 – i.

What is the step-by-step solution to this or any problem like it?

If I find more questions I'll post those too. These were some of the ones I could find for now.

Thanks for the help. It is greatly appreciated... and needed...