1 Equation in ...
1-D Space
1   Variable Unkown
1-D Equation: +2x = +4
1-D Solution:   x = +2
1-D Solution: POINT
2-D Space
2   Variables Unknown
2-D Equation: +2x +0y = +4 
2-D Solution: x = +2
              y = any
2-D Solution: LINE
3-D Space
3   Variables Unknown
3-D Equation: +2x +0y +0z = +4 
3-D Solution: x = +2
              y = any
              z = any 
3-D Solution: PLANE
2 Equations in ...
1-D Space
2   Variables Unkown = Cannot fit
2-D Space
2   Variables Unknown
2-D Equation: +2x -1y = +0
              -1x +2y = +3

            : Each row is an equation
              that represents a LINE

            : 2 LINES meet at 1 POINT
2-D Solution: x = +1
              y = +2

            : Weights of columns
            : Linear combination
2-D Solution: POINT
              Intersect of LINE 1
                           LINE 2
3-D Space
3   Variables Unknown
3-D Equation: +2x -1y +0z = +0
              -1x +2y +0z = +3 

            : Each row is an equation
              that represents a PLANE

            : 2 PLANES meet at 1 LINE
3-D Solution: x = +1
              y = +2
              z = any 

            : Weights of columns
            : Linear combination
            : z Weight for 3rd col = any value
3-D Solution: LINE
              Intersect of PLANE 1
                           PLANE 2