15. Determine whether the solution space of the system Ax = 0 is a line through the origin, a plane through the origin, or the origin only. If it is a plane, find an equation for it. If it is a line, find parametric equations for it. (a) A = ⎡⎢⎣ −1 1 1 3 −1 0 2 −4 −5 ⎤⎥⎦ (b) A = ⎡⎢⎣ 1 2 3 2 5 3 1 0 8 ⎤⎥⎦