# math /algebra

posted by
**Liza** on
.

This was the : Explain why the formula for determining slope using the coordinates of two points does not apply to vertical lines.

This is my answer:The formula for determining a slope using two points does not apply to vertical lines simply because dividing by 0 is not allowed…it is undefined. To find a slope of a horizontal line we use the formula m=y1-y2/x1-x2 this stipulates that we have two points to work with.

Vertical lines are in the form of x=some number, such as x=6; When a line involves an undefined slope the line is vertical, and when a line is vertical you will end up dividing by 0 if you try and evaluate the slope.

Vertical lines have undefined slopes. Thus, the concept of slope simply does not work for vertical lines. A slope of 0=horizontal,

According to page 530 of the text” any two points on a vertical line have the same x coordinate, thus the change in x is always 0, always undefined.

Is this right? If so, do you have any suggestions to make it less wordy and redundant.