Final answer:
The equation of a plane parallel to the x-y plane can be written as: z = k, where k is a constant.
Step-by-step explanation:
The equation of a plane parallel to the x-y plane can be written as: z = k, where k is a constant. This means that the value of z remains the same for all points on the plane.
For example, if we want a plane parallel to the x-y plane through the point (2, 3, 4), the equation would be z = 4.
Similarly, if we want a plane parallel to the x-y plane through the origin (0, 0, 0), the equation would be z = 0.