Mathematics - 3D Coordinate Geometry Question with Solution | TestHub

From $P_2:y=z-4$. Put in $P_1:2x+z-4+z+4=0$, so $x=-z$. Then $P_3:-3z+$ $2(z-4)+z+8=0$ holds for every $z$. So all three planes contain the line $x=-z,y=z-$ 4 , direction $(1,-1,-1)$. The three lines coincide, so they are parallel and the three planes intersect in a line. Options B and C are correct.