Answer
$m=\text{ undefined}$
Work Step by Step
Using $m=\dfrac{y_1-y_2}{x_1-x_2}$ or the Slope Formula, then the slope of the line containing the given points, $\left(
6,-4
\right) \text{ and } \left(
6,5
\right)$, is
\begin{array}{l}
m=\dfrac{-4-5}{6-6}
\\\\
m=\dfrac{-9}{0}
\\\\
m=\text{ undefined}
.\end{array}
