Question

(x,-4) and (2,8); m=_3

Answer 1

$\bf (\stackrel{x_1}{x}~,~\stackrel{y_1}{-4})\qquad (\stackrel{x_2}{2}~,~\stackrel{y_2}{8}) \\\\\\ slope = m\implies \cfrac{\stackrel{rise}{ y_2- y_1}}{\stackrel{run}{ x_2- x_1}}\implies \cfrac{8-(-4)}{2-x}=\stackrel{\stackrel{m}{\downarrow }}{-3}\implies \cfrac{8+4}{2-x}=-3 \\\\\\ \cfrac{12}{2-x}=-3\implies 12=(2-x)(-3)\implies 12=-6+3x \\\\\\ 18=3x\implies \cfrac{18}{3}=x\implies 6=x$