The definition of the slope can be interpreted by the following formula
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]select 2 points from the graph
(2,-1)
(3,-1)
replace in the formula
[tex]\begin{gathered} m=\frac{(-1)-(-1)}{3-2} \\ m=\frac{-1+1}{1} \\ m=\frac{0}{1} \\ m=0 \end{gathered}[/tex]the slope of the line is equal to 0.
