For #4, break up what's under the radical sign into 100 * 2, and then break the n^8 into n^2*n^2*n^2*n^2 so it's easy to see how to pull out what you need to. 100 is a perfect square: 10*10, so you can pull that out, leaving the 2, and you can also pull out 4 n's, so for #4, the answer is 10n^4 sqrt2.
#5 breaks up into 9*7, with 9 being the perfect square 3*3. Break the n^9 up into n^2*n^2*n^2*n^2*n. So you can pull out the 3 and 4 of the n's, which gives you 3n^4sqrt7n