Find the slope of the line (3,-1) and (3,5)?
Slope m= (y2-y1) / (x2-x1)… Rise over run.
However, in this case the change in x will equal zero, and the fraction for m will be undefined. This will be a line with a completely vertical slope.
You could argue that the slope is infinitely large, but it’s the kind of thing that might depend on a particular teacher’s preference. Some might call it undefined.