The position vectors of points a and b are i^−j^+3k^ and 3i^+3j^+3k^ respectively. The equation of a plane is r.(5i^+2j^−7k^)+9=0 . The points a and b
(1) lie on the plane
(2) are on the same side of the plane
(3) are on the opposite side of the plane
(4) None of the above