# What is the slope and y-intercept of the line x=-6?

Jun 12, 2016

The line is vertical.
It does not have a y-intercept at all.
This vertical line does not cross the $y -$ axis anywhere.

#### Explanation:

$x = - 6$ is a vertical line crossing the x-axis at -6.
It does not cross the y-axis at all, so there is no y-intercept.

Lines which are vertical are said to have an infinite or undefined gradient.
The definition of gradient is $\left(\text{change in y-values")/("change in x-values}\right)$

As there is no change in the x-values the denominator would be 0.
Vertical lines are only ones which cannot be written in the standard form of $y = m x + c$ and are always given as $x = \ldots . .$