Question

1. A line passes through the point (2, k) and (4k, 5) and has a slope of 1/2 . Find the value of k.

Answer 1

$(\stackrel{x_1}{2}~,~\stackrel{y_1}{k})\qquad (\stackrel{x_2}{4k}~,~\stackrel{y_2}{5}) ~\hfill \stackrel{slope}{m}\implies \cfrac{\stackrel{rise} {\stackrel{y_2}{5}-\stackrel{y1}{k}}}{\underset{run} {\underset{x_2}{4k}-\underset{x_1}{2}}}~~= ~~\stackrel{\stackrel{m}{\downarrow }}{\cfrac{1}{2}} \\\\\\ 10-2k=4k-2\implies 10=6x-2\implies 12=6k\implies \cfrac{12}{6}=k\implies 2=k$