# 2-4 Writing Linear Equations Using Slope Intercept Form

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```					2-4: Writing Linear Equations
Using Slope Intercept Form
Slope-Intercept Form

• y = mx + b
[or f(x) = mx + b]
• m is the slope
• b is the y-intercept
Find the Equation of the Line

• What is the
y-intercept?
•   b = -2                      x

•   What is m?
3
•   m= 2
3
•   y = 2 x -2           y
Find the Equation of the Line

•b=?
•b=1
x
•m=?
-   1
•m=           2
1
•y=   -       x+1
2             y
Find the Equation of the Line
•   b=?
•   b=4
•   m=?                         x
•   m=0
•   y = 0x+4
• y=4
y
Find the Slope and y-intercept of
each Equation:
3
1) y = -4x + 3 3) 8x + y = 4
m = -4           m = -8
3
b=3              b=4
1
2) y = 5 - 2 x   4) 4x - 2y = 10
1
m=- 2            m=2
b=5              b = -5
Find the Equation Given the
Slope and y-intercept
1) m = -3, b = 1
y = -3x + 1
2
,
2) m = - b = -4
5
2
y=-5x-4
Find the Equation Given the
Slope and a Point
Given m = -1, (2, 1)
First, calculate b by substituting the slope and
the coordinates into y = mx + b.
y = -1x + b
1 = -1(2) + b
1 = -2 + b
3=b
y = -1x + 3
Find the Equation Given
Two Points
Given (-1, 3) and (2, 1)
First, calculate the slope:
(1  3) 2
m           
(2  1) 3
Second, find b. Use either point...
m =  2 , (2, 1)
3
2
1=    (2)      +b
3
4
1 = + b
3
2   7
7
y  x
3 =b                      3   3

```
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