M. (10 pts) Answer True or False. You do not need to provide justifications. (a) If A and B are 33 and B=[b1b2b3] then AB=[b1+b2+b3]. (b) The second row of AB is the second row of A, multiplied on the right by B. (c) (AB)C=(AC)B. (d) (AB)T=ATBT. (e) The transpose of the sum of matrices equals the sum of their transposes. N. (4 pts) Suppose the first two columns of B, ie, b1 and b2, are equal. What can you say about the columns of AB (if AB is defined)