1. **Understanding Vertical Lines:** The equation of a vertical line is $x = c$, where $c$ is a constant. This means that for every point on the line, the $x$-coordinate is the same. The slope of a line measures the change in $y$ over the change in $x$. Since all points on the vertical line have the same $x$-value, the change in $x$ is zero. Hence, the slope formula $m = \frac{\Delta y}{\Delta x}$ involves division by zero, which is undefined. Therefore, vertical lines have undefined slope. 2. **Understanding Horizontal Lines:** The equation of a horizontal line is $y = k$, where $k$ is a constant. For all points on this line, the $y$-coordinate is the same. The change in $y$ is zero, while $x$ can vary. Thus, the slope $m = \frac{\Delta y}{\Delta x} = 0$ because $\Delta y = 0$. Therefore, horizontal lines have zero slope. 3. **Writing Equations of Given Graphs:** - Graph 1 (horizontal at $y = 2$): Equation is $y = 2$ - Graph 2 (vertical at $x = 2$): Equation is $x = 2$ - Graph 3 (vertical at $x = -3$): Equation is $x = -3$ - Graph 4 (horizontal at $y = -3$): Equation is $y = -3$ - Graph 5 (horizontal at $y = 0$): Equation is $y = 0$ - Graph 6 (vertical at $x = 0$): Equation is $x = 0$