[tex]f(\stackrel{x_1}{-4})=\stackrel{y_1}{0}\qquad f(\stackrel{x_2}{0})=\stackrel{y_2}{0}~\hfill (\stackrel{x_1}{-4}~,~\stackrel{y_1}{0})\qquad (\stackrel{x_2}{0}~,~\stackrel{y_2}{0}) \\\\\\ \stackrel{slope}{m}\implies \cfrac{\stackrel{rise} {\stackrel{y_2}{0}-\stackrel{y1}{0}}}{\underset{run} {\underset{x_2}{0}-\underset{x_1}{(-4)}}}\implies \cfrac{0}{0+4}\implies \cfrac{0}{4}\implies 0[/tex]
[tex]\begin{array}{|c|ll} \cline{1-1} \textit{point-slope form}\\ \cline{1-1} \\ y-y_1=m(x-x_1) \\\\ \cline{1-1} \end{array}\implies y-\stackrel{y_1}{0}=\stackrel{m}{0}(x-\stackrel{x_1}{(-4)})\implies \boxed{y = 0}[/tex]
