Final answer:
The equation of the line is x = 3.
Step-by-step explanation:
The equation of the line that passes through the point (3, -8) and has an undefined slope is x = 3.
When a line has an undefined slope, it means that the line is vertical and does not have a defined slope. In this case, the line is parallel to the y-axis and passes through the point (3, -8). Since the x-coordinate is always 3, the equation of the line is x = 3.