it's the slope of a vertical line. the y-coordinate may change but the x-coordinate will never change
Step-by-step explanation: A slope that is undefined means that it has no run. To understand what this means, take a look at the image provided. I have labeled two points along this line and these points are point A and point B.
To get from point A to point B on this line, our rise would be 2 units but our run is 0 units so our slope or rise over run is 2/0. It's important to understand that any number divided by 0 is undefined so the slope of this line or its m would be undefined. As an answer to this problem we say that this line has no slope.
In fact, any vertical or straight up and down line will always have no slope. It's important to understand the difference between a slope of zero and no slope. If a line has a slope of 0, it means that the line is flat or horizontal. No slope means we cannot describe its slope using a number because the line is vertical and its slope is undefined.
