(a) Let c be a constant and consider the matrix A. 3 2 A = and the vector b = Find the determinant of A. For what value(s) of c is A invertible? (5) ii. Assuming that c is a constant for which A is invertible, find A-1 . (Your answer should contain c) (6) iii. Use the inverse matrix to find the solution of Ax = b, for any value of c for which the inverse exits. (3) (b) With respect to a fixed origin O, the lines /, and /, are given by the equations 2 N 4: r= 5 + 1 -1 4 : r= -2 + 1 where 1 and / are scalar parameters and b is a constant. Prove that for all values of b # 7, the lines , and I, are skew. (6)