[tex](\stackrel{x_1}{7}~,~\stackrel{y_1}{-4})\qquad (\stackrel{x_2}{2}~,~\stackrel{y_2}{-4}) \\\\\\ \stackrel{slope}{m}\implies \cfrac{\stackrel{rise} {\stackrel{y_2}{-4}-\stackrel{y1}{(-4)}}}{\underset{run} {\underset{x_2}{2}-\underset{x_1}{7}}}\implies \cfrac{-4+4}{5}\implies \cfrac{0}{5}\implies 0[/tex]
yes, is a vertical line, and all vertical lines have that slope.
