Question 670771
If the slope m is undefined, then only one thing is possible: you are dividing by zero.


The only way this can happen is if x2 - x1 = 0


So...


r - 1 = 0


r = 1


The equation of this line is then x = 1 since this is a vertical line (with undefined slope) that goes through both (1, 4) and (1,5)