Question

what is the slope of the line through the points (2/3,4/7) and 2/3,11/7)??
...undefined
...2/3
...1
...0

Answer 1

Undefined because it is a vertical line

Answer 2

Yep. It's undefined. You subtract the x's, and you get a zero on bottom. IMPOSSIBLE, YOU SAY?? Well, it happened. So, that's the answer