Answer
$$\text{slope is undefined}$$
Work Step by Step
RECALL:
The slope $m$ of the line that contains the points $(x_1, y_1)$ and $(x_2, y_2)$ can be found using the formula:
$$m=\dfrac{y_2-y_1}{x_2-x_1}$$
Use the formula above to obtain:
$$m=\dfrac{-2-6}{5-5}
\\m=\dfrac{-8}{0}
\\\text{slope is undefined}$$