Kevin C. answered 04/15/13
Successful Math Tutor -- Recently retired high school math teacher
What this equation is saying is that no matter what the value of y is in the ordered pair (x, y), the value of x is 4. Therefore, if you graph the points (4, 0), (4, 3) and (4, 5), or any point with the x-coordinate 0, we will have a vertical line. It's always best to use at least 3 points to make sure we have a straight line in a linear equation.
i hope this helps.
Kevin