Question

Find the x value do that the line through the points (x,-9) and (0,1) has a slope of -4 PLEASE ANSWER

Answer 1

$\bf (\stackrel{x_1}{x}~,~\stackrel{y_1}{-9})\qquad (\stackrel{x_2}{0}~,~\stackrel{y_2}{1}) \\\\\\ slope = m\implies \cfrac{\stackrel{rise}{ y_2- y_1}}{\stackrel{run}{ x_2- x_1}}\implies \cfrac{1-(-9)}{0-x}=\stackrel{\stackrel{slope}{\downarrow }}{-4}\implies \cfrac{1+9}{-x}=-4 \\\\\\ \cfrac{10}{-x}=-4\implies 10=4x\implies \cfrac{10}{4}=x\implies \cfrac{5}{2}=x$