I need some data that could help me explain the following:

Question

Why the line x = 4 is a vertical line?

Answer 1

at x=4, y=0. if y=0, there is no y vlaue to "slope" the line, so the line will form vertically at x=4.

Answer 2

X = 4 for all values of Y.

I hope this helps a little more. Thanks for asking.