Solve the system by back substitution. 2x + 4y +z +3w = - 2y - 12z - 4w = - 16 - Z-W = -2 - 3w= -9 The solution set is {0000)-(Type an integer -9 0 Let A= 2 -6 Find - 5A - 5A= 0 Perform the indicated operation if possible. 1 1 -3 6 2 -5 - 11 0 -6 -5 -2 0 3 Select the correct choice below and, if necessary, fill in the answer box to com O A. The resulting matrix is (Simplify your answer.) OB. The resulting matrix does not exist because the operation is not possib