8√8 = 8(√4 x 2) (you can take the root of 4 out of the bracket) 8 x 2(√2) = 16√2
1/8√8 (to rationalise multiply by √8/√8 to eliminate the √8 from the denominator and so that it is only multiplied by 1 so has to be √8/√8) 1/8√8 x √8/√8 = 1√8/(8 x √8 x √8) = 1√8/(8 x 8) = 1√8/64