All you really have to do is find the prime factorization of the term. And for every pair of like factors you can move that term outside of the radical sign (for square roots) If you were doing cube roots you would need to find threesomes of factors... for example..
20^(1/2)
pf 20=225 so you have two twos so you can simplify to 2(5)^(1/2)
108^(1/3)
pf 108=22333 so you have 3^3 so you can simplify to 3(4)^(1/3)
