Question

What is the equation of the line that passes through the point (4,-2) and has an undefined slope?

Answer 1

Answer: x = 4

Reason:

All lines that have undefined slopes are vertical.

Vertical lines are of the template x = h, for some fixed value h. We must have h = 4 so we arrive at the answer x = 4

All points on this particular vertical line have an x coordinate of 4. Two example points are (4,-2) and (4,5)