Respuesta :

It's undefined, but I think you spelled it wrong.
Slope = (y2 - y1) / (x2-x1)
Here, you can see line is parallel to y-axis, so it's x-coordinates is same for every point.

It means, (x2 - x1) = 0
So, m = (y2-y1) / 0
As 0 is in denominator, it is undefined

Hope this helps!