2.2 Slope of a Line
Slope
vertical  change rise
m

horizontal  change run
Meet Joe….Joe Cool
• Joe has a disease, he
can only walk to the
right.
• Use Joe to help you find
the slope
• Always start on the left
to help Joe walk to the
right
“slope”
5
4
3
2
1
-6
-4
-2
2
4
-1
-2
-3
change in " y" 2 rise

slope 
change in " x"
3 run
-4
-5
6
Graph the line containing the points
(-4,2) and (2,-3) and find the slope.
5
4
change in " y"  5

slope 
6
change in " x"
3
2
1
-6
-4
-2
2
-1
-2
-3
-4
-5
4
6
Slope of a Horizontal line (y=#)
Always 0
HOY
H: horizontal line
0: 0 slope
Y: y= #
What is the slope?
(-6,4)
y2  y1
m
x2  x1
(5,4)
Horizontal line = “0” slope
Slope of a Vertical Line (x=#)
Always Undefined
VUX
V: Vertical Line
U:Undefined slope
X: X=#
What is the slope?
y2  y1
m
x2  x1
(3,8)
(3,-2)
Vertical line = “undefined”
Slope Formula
given : ( x1, y1 )and ( x2 , y2 )
y2  y1
m
x2  x1
Find the slope of the line containing
(2,2) and (8,9)
y2  y1
slope ("m") 
x2  x1
9-2 = 7
8-2 6
Find the slope of the line containing
(-4,-6) and (3,-2)
y2  y1
slope ("m") 
x2  x1
M= -2 - -6 = -2 + 6 = 4
3 - -4
3+4
7
Find the slope of the line containing
(1,1) and (3,5)
y2  y1
slope ("m") 
x2  x1
5 1
4 2
m
 
3 1
2 1
Find the Slope from a table
+1
Hours
(x)
Feet
(y)
change  in  y
change  in  x
+1
+1
1
2
3
4
-12
-14
-16
-18
-2
-2
-2
2
1
A line contains points (5, 3) and (x, 9) and has
slope = 3. Find the value of x.
3= 9-3
x-5
3= 6
x-5
3x 15  6
3x  21
x7
A line contains points (9, -5) and (-8, k) and
has slope = 0. Find the value of k.
5  k
Homework
TB: Page 53 (1-3 all, 7-18 all, 22-34 even)
Adventures of Slope Dude
• http://www.youtube.com/watch?v=ZzU8x5cM
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