Solve the given inequality $x+y \geq 4$ graphically in two – dimensional plane.
The graphical representation of $x+y \geq 4$ is given by blue line in the figure below.
This lines divides $x-y$ plane into two parts
Select a point (not on the line),which lies on one of the two parts, to determine whether the point satisfies the given inequality or not.
We select the point as $(0,0)$
It is observed that $0+0 \geq 4$ or $0 \geq 4$ which is false.
Therefore, the solution for the given inequality including the points on the line.
This can be represented as follows,