How do you graph #x=0#?
This is the equation of the y-axis. It is a vertical line through the origin.
Any vertical line has the equation
This is because it only has an x-intercept and does not intersect they-axis.
Vertical lines cannot be written in standard form because the slope is undefined.
The equation of the line is given by the x-intercept of the line.
In this case
[In the same way the equation of the x-axis is