Find the vector form of the general solution of the given linear system Ax = 1; then use that result to find the vector form of the general solution of Ax = 0
(a) x1 - 3x2 = 1
2x1 - 6x2 = 2
(b) x1 - 2x2 + x3 + 2x4 = - 1
2x1 - 4x2 + 2x3 + 4x4 = - 2
3x1 - 6x2 + 3x3 + 6x4 = - 3