3. (a) Let A = (2 1) . B - (3 3) .C - (6 o') Calculate the following or explain why they are not defined: (i) det(A) + det (BC). [2 marks] (ii) ATB - C2. [2 marks] (iii) A-1. [4 marks] (iv) If D is a 2 x 2-matrix such that B = DA, find D. [4 marks] (b) Let X = HOL CO NO (i) Calculate the determinant of X. [4 marks] (ii) Calculate the inverse X-1 of X. [4 marks]