the normal vectors of the planes are: , ,
These vectors are linear independent(?) and the planes have one common point
These vectors are linear dependent(?) because the following equation has a unique solution:
. This equation is true for r = 1 and s = 2.
First guess: The planes intersect in a common line.
According to my calculations the three planes are not parallel and there doesn't exist a common line thus they intersect in three different parallel lines.
EDIT: I've attached a diagram of the three planes.