Answer:
Step-by-step explanation:
Slope is defined as the "Rise" over the "Run" of a straight line. The Rise is the change in y, and the Run is the change in x. For the given points:
(5,6) and (5,9) the Rise and Run are (going from left to right).
Rise (9-6) = 3
Run = (5-5) = 0
The slope is 3/0, which is undefined (can't divide by zero).