Question

Describe the slope of two points.
Marcus plots the point (4, 7) in Quadrant I on the coordinate plane. Nicole then plots the point (4, –3) in Quadrant IV of the same graph. Explain what the line that goes through those two points would look like, and evaluate the slope.

Answer 1

Both points have the same x-coordinate (4), so the line through them is the vertical line x = 4. It runs straight up and down, passing through (4,7), (4,0), and (4,−3).

Slope m = (change in y)/(change in x) = (−3 − 7)/(4 − 4) = −10/0, which is undefined. Vertical lines have undefined slope (you cannot divide by zero).