In order to subtract matrices, they have to have the same dimensions, which this problem provides(both 3x3) Then, just subtract the numbers on the right from the corresponding numbers on the left. Example: -3-12=-15, which is the top left answer. Repeat with all positions.
Break the numbers under the radical into perfect squares: . Take the perfect squares out: you have two 2's, and 2 x's, on the outside of the radical with 2 and z leftover: . Multiply everything together to get .