The formula used to calculate the slope of a line given the coordinates on the line is given to be:
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]Given the points:
[tex]\begin{gathered} (x_1,y_1)=(8,9) \\ (x_2,y_2)=(8,1) \end{gathered}[/tex]Therefore, we can calculate the slope to be:
[tex]\begin{gathered} m=\frac{1-9}{8-8}=\frac{-8}{0} \\ m=undefined \end{gathered}[/tex]Therefore, the slope is undefined.
