Let A (1 1 2-1). B=(2 1 1 3). (a) If bk = B(:, k) denote the columns of B, then calculate Ab1 and Ab2. (b) If aT k = A(k, :) denote the rows of A, then calculate aT 1 B and aT 2 B. (c) Compute AB, entry-by-entry multiplying rows of A into columns of B. Verify that its column vectors are the vectors in (a) and its row vectors are the vectors in (b).