6 (3) Let A = 1 -1 and u= -3 23 3 C = 5 15 (a) Compute Au and Ac, if possible. If not possible, explain why not. (b) Does the matrix equation Ax (c) Does the matrix equation Ar = = c have a solution? b have a solution for any choice of be R3? (d) Restate the above question as a computationally equivalent question (as done in page 2 of the notes).