Question

Find the slope of the line through the pair of points. A(2, –3), P(2, 9)

Answer 1

we are given with two points and is asked for the slope of the line formed by the two points. The formula of the slope is equal to change in y over change in x. In this case, the slope is (9+3)/(2-2) equal to 12/0 equal to infinity. This means the line connecting the two is a vertical line 

Answer 2

The slope:
`m=(y_2-y_1)/(x_2-x_1)`


`A(2;-3)\to x_1=2;\ y_1=-3\\P(2;\ 9)\to x_2=2;\ y_2=9\\\\subtitute:\\\\m=(9-(-3))/(2-2)=(12)/(0)!!!`

The denominator can not be zero!

Conclusion: The slope is undenfined.