Math 60
7.3: Slope
Elementary Algebra
Slope (m) is the ratio of (vertical) rise to (horizontal) run.
m
y y2  y1

, where  x1 , y1  and  x2 , y2  are any two points on the line.
x x2  x1
5
(6, 4)
Slope =
4
rise
run
Vertical RISE
3
(2, 2)
Horizontal RUN
2
(6, 2)
1
1
2
3
4
5
6
Compute the slope of the line passing through (– 3, – 5) and (– 6, – 8).
Write the equation of the line in slope–intercept form.
m = __________
y = mx + b  y = __________________
But what about the slopes of vertical and horizontal lines? Let’s consider two examples:
Slope of a Vertical Line
Vertical lines look like:
x=
Consider: x = 3
Let’s plot (3, 0) and (3, 4), then compute the slope.
m
y2  y1
x2  x1
Slope of a Horizontal Line
Horizontal lines look like:
y=
Consider: y = 5
Let’s plot (2, 5) and (6, 5), then compute the slope.
m
y2  y1
x2  x1