1) If the origin and the points P(2,3,4) , Q(1,2,3) and R(x,y,z) are coplanar, then A) x-2y-z=0 B) x+-2y+z=0 C) x-2y+z=0 D) 2x-2y+z=0 Answer: Option CExplanation:Let O (0,0,0) be the origin , It is given that O(0,0,0) , P(2,3,4), Q(1,2,3) and R(x,y,z) are coplannar ∴ [OR OP OQ] [x−0y−0z−02−03−04−01−02−03−0]=0 [xyz234123]=0 x(9-8)-y(6-4)+z(4-3)=0 ⇒ x-2y+z=0