First let's take a look at the point (-5,-2) in the plane:
since we want an equation of a line that is perpendicular to the x-axis, it should look like this:
Therefore, the equation is x = -5. Now for the slope, we can easily see that the line passes through the points (-5,-2) and (-5,-3), so, if we calculate the slope we get something like this:
[tex]\begin{gathered} m=\frac{y_2-y_1}{x_2-x_1}_{} \\ \Rightarrow m=\frac{-3.-(-2)}{-5-(-5)}=\frac{-3+2}{-5+5}=-\frac{1}{0} \end{gathered}[/tex]which clearly is undefined.