Final answer:
The line containing point P and having an undefined slope is x = -8.
Step-by-step explanation:
The given question asks to graph a line containing the point P(-8,-7) and having an undefined slope. Now, when the slope is undefined, it means that the line is vertical. In a vertical line, the x-coordinate remains constant while the y-coordinate can take any value. So, the equation of the line containing P with an undefined slope is x = -8.