Answer
$m=-3$
Work Step by Step
Using $m=\dfrac{y_1-y_2}{x_1-x_2}$ or the Slope Formula, then the slope, $m$, of the line containing the given points, $(
1,2
)\text{ and } (
4,-7
)$, is
\begin{array}{l}
m=\dfrac{2-(-7)}{1-4}
\\\\
m=\dfrac{2+7}{1-4}
\\\\
m=\dfrac{9}{-3}
\\\\
m=-3
.\end{array}
