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.