Chapter 8 - Coordinate Geometry and Linear Systems - 8.3 - Slope of a Line - Problem Set 8.3 - Page 349: 11

$m=0$

Using $m=\dfrac{y_1-y_2}{x_1-x2}$ the slope of the line determined by the given points, $( 3,-4 ) \text{ and } ( 2,-4 ),$ is \begin{array}{l}\require{cancel} m=\dfrac{-4-(-4)}{3-2} \\\\ m=\dfrac{-4+4}{1} \\\\ m=\dfrac{0}{1} \\\\ m=0 .\end{array}