Chapter — Graphng
Model 4
What is the equation of a line with a slope of –2 and a y-intercept of (0, 4)? Use the slope-intercept form
for your answer.
m = –2, b = 4, slope-intercept equation form: y = mx + b
Replace m and b with the given values: y = (–2)x + (4)
Slope-intercept form: y = –2x + 4
Model 5
y
Using the graph of the equation 2x + 2y = 6 shown at right,
do the following:
a. Plot and label the ordered pair solutions: (0, 3), (1, 2),
and (2, 1).
b. Label the x and y-intercepts.
x
c. Calculate the slope of the line. Validate your work.
y
(0, 3)
x
+
=
The y-intercept was given. Find the
2
2 0
( )
6
y-intercept
(1, 2)
x-intercept. Let y = 0 and solve for x:
2
x
=
6
(2, 1)
6
x-intercept
x
x
=
=
3
2
(3, 0)
The x-intercept is (3, 0)
y
y
(
−
)
Validate:
Use (0, 3) and (1, 2) to
m
=
2
1
(
x
−
x
)
calculate the slope:
2
1
Use (2, 1) and (0, 3) to
(2 3)
−
(
y
−
y
)
m
=
m
=
recalculate the slope:
2
1
(1 0)
−
(
x
−
x
)
2
1
−
1
(3 1)
−
slope
–1
=
=
m
=
1
(0 2)
−
2
slope
=
=
–1
−
2