Final answer:
A line that has an undefined slope is vertical. The equation of the vertical line passing through (1, -2) is x = 1.
Step-by-step explanation:
The equation of a line with an undefined slope is a vertical line. When a line passes through a specific point and has an undefined slope, the equation of that line is simply 'x' equal to the x-coordinate of the given point. Since the line passes through the point (1, -2), the equation of the line is x = 1.