2. (5%) Let A and B be two matrices such that the matrix product AB is well deined. Then, rank(AB) ＞ rank(A) and rank(AB) ＞ rank(B).

8. (5%) Consider a system of linear equations At = b, where A is a 2 x 3 matrix, I is a 3 x 1 column vector, and b is a 2 X 1 column vector. LetIn other words, all entries of A are non-zero. Then, it is impossible to uniquely determine t1 from the above system of linear equations.