The meaning of a matrices

Matrices can be considered as a system that describe a set of points in n-dimensional space.

Let's consider these equations


1.)this equation describe a set of points in a 3-D space. More specifically, it appears as a plane.


2.)this equation describe another set of points in a 3-D space too.



3.) this two equations describe a new set of points in space. More specifically, "it" together appears upon us as a line, rather than two isolated planes.


4.) If there is a new equations such that the unknowns can be solved.
Then these equations becomes in a way:

Are those equations same as before? What are the meanings of them?

The answer is no for the latter two. They are NEW sets of points in a 3-D space (geometrically planes) by each of them independently.
All three of them together are described as, merely, ONE point in space.