1 2 Solve for all matrices C so that BC C B The proof of theorem 3 2 5 depends on how one approaches the subject it can either be a definition or a theorem But for us one would have to write out an arbitrary matrix and check the properties From there we can deduce an additional property as explained below Exercise 3 6 2 Consider the matrix B Theorem 3 6 3 If A E Matmxn and 0 Proof O A 0 ER then A 0 0 Rm Othm 325 a