## Intermediate Algebra (6th Edition)

We are given that $x+2=0$, which also can be written as $x=-2$. To find the slope of a line, we can take two points on the line and calculate the slope using the slope formula. $m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}$ We know that two points on this line will be (-2,0) and (-2,4), since all points on this line will have an x-coordinate of -2, no matter the value of y. $m=\frac{4-0}{-2-(-2)}=\frac{2}{-2+2}=\frac{2}{0}$ So the slope of this line is undefined. In general, the slope of a vertical line, which is in the form $x=c$, has an undefined slope.