The important information in this chapter is summarized below.
For a straight line, slope is equal to rise over run, or
Change in y
Change in x
Since slope m is a measure of the steepness of a line, a slope has the following
A horizontal line has zero slope.
A line that rises to the right of vertical has positive slope.
A line rising to the left of vertical has negative slope.
A vertical line has undefined slope because the calculation of the
slope would involve division by zero (Dy/Dx approaches infinity as
the slope approaches vertical).