Rules you need to know:

to learn how to convert roots to powers so you can apply the rules above, see here

so, that should take care of question 3, try it

for question 4:

(a)

notice that ......this is a quadratic

(b)

notice that .........factor out the common term

(c) try a similar maneuver as in (a)

(d)

factor out the lowest power of , that is,