Page 291 - Algebra 1

Two points are not always given explicitly as coordinates to determine
the slope. If given a table or graph then two points must be chosen in order to use the slope formula.
Determining Slope From a Table
Determine the slope of the line that contains the given points shown in the table.
Example
2
Math Reasoning
Verify Choose another set of points from the table to verify that the
slope is -_2 . 5
x
y
-5
6
10
0
40
-12
SOLU_TION y2 - y1
m=_ x2 - x1
slope formula
Substitute coordinates of 2 ordered pairs.
Simplify.
= 0 - 6 10 - (-5)
= -6 _
15
= -_2 5
The slope of the line is -_2 . 5
Determining Slope from a Graph
Determine the slope of the given line.
Example
3
y
a.
SOLUTION
b.
SOLUTION
8
(-2, 7)
x
-8
-4
8
-8
-4
-4
4
(3,
-3)
8
-4
(1,
-5)
276 Saxon Algebra 1
-8
__ m= y2 -y1 slopeformula m= y2 -y1
x-x x-x 21 21
__
= (-3)-7 Substituteinx- = 5-(-5)
3 - (-2) and y-values. 3 - 1 = -10 = 10
__ 52
= -2 Simplify. = 5
The slope of the line is −2. The slope of the line is 5.
-8
8
4
y
(3,
5)
x
4