Download Graphing lines using slope intercept form

4.7 Graphing Lines Using
Slope Intercept Form
Goal: Graph lines in slope
intercept form.
Slope-Intercept Form of the Linear
Equation
y=m
mx + b
= slope
= y-intercept
Any linear equation which is solved for y
is in slope-intercept form.
Find the slope and y-intercept of the
following linear equations:
y = -2x - 1
m = -2 b = -1
y = 5x
y = 3x + 4
m=3 b=4
1
2
y= x9
4
2
m=
9
1
b=
4
m=5 b=0
Write a linear equation in the form
y = mx + b given the following.
m = 2, b = -3
y = 2x - 3
2
m=
,b=5
3
2
y  x5
3
Graph the following linear equation using slope
and y-intercept.
2
y
Steps
3
x 1
y
1) Find the slope and y-intercept.
2 b  1
m
+3
3
+2
2) Plot the y-intercept.
3) Plot the slope.
2
2
m = or m = -3
3
4) Draw line through points.
-2
-3
x
Graph the line which passes through
(-2, 1) and has a slope of -3.
Steps
y
1) Plot the point.
2) Write slope as fraction
and count off other points.
-3
-3
m = -3 =
1
3
+1
or m =
-1
3) Draw line through points.
x
Graph the line which passes through (3, 2) and
3
has a slope of
.
4
Steps
y
+4
1) Plot the point.
2) Write slope as fraction
and count off other points.
3
m=
4
-3
or m =
-4
3) Draw line through points.
+3
x
Write a linear equation in slope-intercept form
to describeyeach graph. y = mxy+ b
8
x
x
-6
4
2
m
1
b=3
y = 2x + 3
2
b = -4
1
m
3
1
y   x4
3
Parallel Lines
Graph the following on the coordinate plane.
1
y  x3
2
1
m
2
b  3
y
1
y  x 1
2
1
m
x
2
b  1
Parallel lines have the same slope.
Tell whether the lines below are parallel.
1) 3x + y = 7
-3x
-3x
y = -3x + 7
y = mx + b
m = -3
y = -3x + 1
m = -3
Same slope!
Lines are parallel!