I've attached 2 images above. The first is the problem itself and the answer. It's question 9. So, I tried solving this question using the method of finding the inverse of a n x n matrix by augmenting it with the identity matrix of the same dimensions and then applying row ops in an attempt to change the matrix on the left of the augmentation (the given matrix) to the identity matrix. I then though I would have some conditions for b. I'm not sure if I've just made a mistake in my calculations or whether my general approach is off. Any help would be much appreciated.