recall the previous posting, parallel lines have the same slopes, notice the slopes of these two
[tex]\bf \begin{array}{|c|ll} \cline{1-1} slope-intercept~form\\ \cline{1-1} \\ y=\underset{y-intercept}{\stackrel{slope\qquad }{\stackrel{\downarrow }{m}x+\underset{\uparrow }{b}}} \\\\ \cline{1-1} \end{array}\qquad \qquad \begin{array}{llll} y=\stackrel{\stackrel{m}{\downarrow }}{-4}x-1\\\\ y=\stackrel{\stackrel{m}{\downarrow }}{-4}x+2\\\\ \textit{\large parallel lines} \end{array}[/tex]
