Download Slope-Intercept Form

Slope-Intercept Form of
a Linear Equation
y = mx + b
bkevil
y = mx + b

This is called the slope-intercept form
of a linear equation because:
You can see the slope (m)
 You can see the y-intercept (b) (0, b)
 x and y represent all the (x, y) order
pairs that graph points


In this form the function can be
easily graphed on the calculator.
bkevil
Give the slope and y-intercept
of each:





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1.
2.
3.
4.
5.
6.
bkevil
y = -2x + 1 m = -2 (0, 1)
m=1
(0, 5)
y=x+5
2x + 3y = 6 m = -2/3 (0, 3)
-6x – 2 = y
m = -6
(0, -2)
y=2
m=0
(0, 2)
x = -3 This equation cannot be put into
slope intercept form – slope is
undefined & no y-intercept
Graphing a Line Using
Slope-Intercept Form
y = 3x - 2
y
1st Put equation into
y=mx + b form
y = 3x - 2
x
2nd Plot y-intercept
(0, -2)
3rd Count slope --rise 3, run 1 and
plot more points
4th Draw the line
bkevil
Graph Using Slope-Intercept
y
1
y  x3
2
1st Equation is in
y=mx + b form
2nd y-intercept = 3
Plot (0, 3)
3rd slope = m= -1/2
-- rise -1, run 2 and
plot more points
4th Draw the line
bkevil
x
1
y  x3
2
.
Check out graph on the
Calculator



Go to y1=
Type in equation
Set window
bkevil

Graph
Write an equation for the graph:
y
Eq: y =-3/2 x + 1
.
bkevil
(0,1)
.
x
.
Eq: y = mx + b
Count slope between
two points: m=-3/2
Identify y-intercept:
b= 1 (0,1)
Substitute values for m
and b into equation:
Eq: y =-3/2 x + 1
Write the Equation of a line
given– slope & y-intercept
Given:
point (0, 5) & slope m = -½
Write the equation of the line.
y= mx+ b
y = -½ x + 5
y = -½x + 5
bkevil
1st Write equation into
y=•
x + form
2nd Plug in slope m
(coefficient of x)
3rd Plug in slope b
(y coordinate of pt. (0, b)
4th Equation is in
slope intercept form
Write the Equation of a line
given– slope & a point
Given: point (-2, 5) &
slope m = -3
Write the equation of the line.
y= mx+ b
y = -3 x + b
5 = -3(-2) + b
5=6+b
-1 = b
y = -3x - 1
bkevil
1st Write equation into
y=•
x + form
2nd Plug in slope m
(coefficient of x)
3rd Plug x and y from
the given point
4th Solve for b
5th Plug m & b into
y=•
x+
The end
bkevil