[tex]\bf (\stackrel{x_1}{-2}~,~\stackrel{y_1}{2})\qquad (\stackrel{x_2}{-2}~,~\stackrel{y_2}{-3}) \\\\\\ slope = m\implies \cfrac{\stackrel{rise}{ y_2- y_1}}{\stackrel{run}{ x_2- x_1}}\implies \cfrac{-3-2}{-2-(-2)}\implies \cfrac{-5}{-2+2}\implies \stackrel{und efined}{\cfrac{-5}{0}}[/tex]
when we have an undefined slope, it means simply is a vertical line, check the picture below.
