# How do you find the slope of the line x=-7?

Aug 1, 2015

This is a vertical line so has undefined slope.

#### Explanation:

If a line passes through points $\left({x}_{1} , {y}_{1}\right)$ and $\left({x}_{2} , {y}_{2}\right)$ then its slope $m$ is given by the formula:

$m = \frac{\Delta y}{\Delta x} = \frac{{y}_{2} - {y}_{1}}{{x}_{2} - {x}_{1}}$

In the case of the line $x = - 7$, let us use the distinct points $\left(- 7 , 0\right)$ and $\left(- 7 , 1\right)$ in this formula to find:

$m = \frac{{y}_{2} - {y}_{1}}{{x}_{2} - {x}_{1}} = \frac{1 - 0}{- 7 - \left(- 7\right)} = \frac{1}{0}$ which is undefined.