1) I don't know how to make it pretty, so I hope this works: First foil it:

Now you need to simplify and

This is how I do it: Take sqrt(8) and break it into it's factors, so you have:

Make sense? So if you do that we have:

Now you can just simplify:

2) This one is a cinch:

Do you see why?

3) This is the same as 2.

4) You need to break sqrt(35) into it's factors:

Now we have:

The two sqrt(7)s just cancel out.