Answers to starred exercises with some hints and solutions
Chapter 1. Vectors and matrices
(iv) C + D is nonsense because C is 3 × 3 and D is 3 × 1.
(vii) B is not square, so B + 3I is not defined.
(xiii) C A is nonsense because C is 3 × 3 and A is 2 × 3.
(xviii) det(A) is nonsense because A is not square.
(xix) det(B) is nonsense because B is not square.
(xxii) det(C D) is nonsense ...