Answer:
The slope of the line is undefined, and the equation of the line is x = 9.
Step-by-step explanation:
Given the points
Finding the slope between (9, 4) and (9, -5)
It is clear that the value of x = 9 is the same in both points.
It means no matter what the value of y is, the value of x remains the same.
It means the line is vertical.
Therefore, the slope of the vertical line is undefined, because the value of x is not changing.
Thus, the slope of the line is undefined, and the equation of the line is x = 9.
