Answer and Explanation

Our problem is:

What is the slope of a line that has coordinates (5, 18) and (5, -12)?

For tackling this problem, apply the formula:      [tex]m=\displaystyle\frac{y_2-y_1}{x_2-x_1}[/tex].

Plug the numbers instead of the variables:           [tex]m=\displaystyle\frac{-12-18}{5-5}[/tex]

Finish solving:         [tex]m=\displaystyle\frac{30}{0}[/tex]

You may have noticed by now that we are dividing by zero - that is an operation we can't do. So the slope is Not Defined.