Final answer:
The line with the equation x=-5 is a vertical line, hence its slope is undefined because the change in x is zero and the change in y is not finite, which results in division by zero.
Step-by-step explanation:
If mm is the line with the equation x=-5, we are dealing with a vertical line. Vertical lines do not have a defined slope since they go straight up and down, meaning their rise over run is not a finite number. When we talk about the slope of a line in the context of an equation like this, we consider the change in y over the change in x. Here, since the change in x is zero (the line does not move left or right), the slope is considered to be undefined. Thus, the correct answer to the question about the slope of the line with the equation x=-5 is that the slope is undefined.