Beginning Algebra With Applications, Chapter 5, Cumulative Exercises, Section Cumulative Exercises, Problem 12

Determine the slope of the line that contains the points whose coordinates are $(2,3)$ and $(-2,3)$.

We let $(x_1, y_1) = (2,3)$ and $(x_2, y_2) = (-2,3)$,

Using the formula for the slope of a line


$\begin{equation} \begin{aligned} m =& \frac{y_2 - y_1}{x_2 - x_1} \\ \\ m =& \frac{3-3}{-2-2} \\ \\ m =& \frac{0}{-4} \\ \\ m =& 0 \end{aligned} \end{equation}$


Then using Point Slope Formula, where $(x_1, y_1) = (2,3)$ and $m=0$


$\begin{equation} \begin{aligned} y - y_1 =& m(x - x_1) \\ y - 3 =& 0 (x-2) \\ y-3 =& 0 \\ y =& 3 \end{aligned} \end{equation}$



The equation of the line is $y=3$.