Question

What do you know about the slope when X2 - X1 = 0 ?

Answer 1

slope is undefined

Explanation:

Using the slope formula

m = (y₂ - y₁ ) / (x₂ - x₁ )

If x₂ - x₁ = 0

Since division by zero is undefined then the slope of the line is undefined

This applies to a vertical line parallel to the y- axis