Let A,B,C and D be matrices of orders 4×3,3×2,2×4 and 4×4 respectively.
(a) For each of the following single products, state with reason whether it is defined and, if so, give the order of the result:
AB,AC,AD,BA,BD,CB,CD,DC.
(b) List all products of two matrices among A,B,C,D whose result is of order 4×4.
(c) Decide which of the following sums can be carried out. Whenever a sum is possible, give the common order of the addends:
(i) AB+D(ii) AC+C(iii) BD+DC(iv) CB+AB.