Answer: Undefined
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Step-by-step explanation:
Both points have the same x coordinate, which immediately tells us both points are on the same vertical line.
All vertical lines have an undefined slope. This is because when it comes to rise/run, the "run" is zero. Dividing by zero is not allowed.
Check out the steps below.
The "UND" is shorthand for "undefined". Some textbooks may use the notation "NaN" to refer to "not a number".