Stack and Subtract/Rise over Run
to find slope
notes
Absent copy
Mon 4/15
Stack and subtract to find slope
Here are 2 ordered pairs that can be graphed:
(3,4) (5,2)
you can find the slope of this
line by stacking the ordered
pairs and subtracting the x’s and y’s.
Then put the new y on top of the new x.
x
3 , 4 
(3,4)
- (5,2) Hint: what happens with the – sign outside of the grouping?
(-2,2)
y = 2
Slope is -1
x,y
x -2
5 , 2 
Example 1
• Find the slope of the line
that goes through the
following points.
(-4,8) and (5,-1)
(-4,8)
- (5,-1) distribute the neg.
(-4,8)
+(-5,1)
-9, 9
x,y
Slope is 9
or -1
-9
• Does it matter what
ordered pair we stack first
when using the stack and
subtract method to find
slope?
YES or NO
• What do we have to do with
the neg. sign outside of the
groupings?
•
You have to distribute the neg. sign
through the parenthesis then rewrite.
• How do we write the slope
y or x
x
y
Example 2
• Find the slope of the line
that goes through the
following points.
(-3,3) and (2,1)
( 2, 1)
-(-3,3) distribute the neg.
( 2, 1)
+( 3,-3)
(5, -2)
x, y
Slope:
-2
5
• Does it matter what
ordered pair we stack first
when using the stack and
subtract method to find
slope?
YES or NO
• What do we have to do with
the neg. sign outside the
groupings?
•
You have to distribute the neg. sign
through the parenthesis then rewrite.
• How do we write the slope
y or x
x
y
Rise over Run method to find slope
count the change in y = Rise
count the change in x Run
4 = -2
2
slope is -2
Example 3
• Identify the slope of
the line.
• What do we all ready know
from the direction of the
line?
•

That the slope is neg.
• What is the change in y?
3,5 
•
2 ,0 
• What is the change in x?
•
5 = 1
5
Slope is____-1_____
The change in y is 5.
The change in x is 5.
• How do we write the
solution to the slope?
y or x
x
y
Example 4
• Identify the slope of
the line.
  1, 5 
• What do we all ready
know from the direction
of the line?
•
The slope will be positive.
•
The change in y is 8.
•
The change in x is 2.
• What is the change in y?
• What is the change in x?

3,  3 
slope
8 =4
2
• How do we write the
solution to the slope?
y or x
x
y