RREF(A)= [1 0 0 0 0 0 1] [0 1 0 0 0 1 0] [0 0 1 0 1 0 0] [0 0 0 1 2 3 4] RREF(B)= [ 1 0 0 6 -3] [ 0 1 0 5 7] [ 0 0 1 2 4]