1. Ch 4.3 (Extra) Writing Equation from Standard to Slope-Intercept
Objective:
To rewrite an equation from standard form
to slope-intercept form.

2. Definitions
Standard Form Slope-Intercept Form Ax + By = C y = mx + b
Rules
Goal: Isolate “y”
Subtract “Ax” from both sides
Divide EVERYTHING on both sides by “B”

3. } -3x -3x -3 Example 1 Write 3x + 2y = 8 in slope-intercept form.
Standard Form
Slope-Intercept Form
y = mx + b
Ax + By = C
3x + 2y = 8 -3
-3x x
y = x
+ 4 2
2y = -3x + 8
To graph:
Go up 4 units from origin (0,0) then
“rise” -3 units and “run” 2 units -3
y = x + 4 2 }
down 3 units
To change Standard Form to Slope-Intercept Form
just solve the equation for y.

4. Example 2
Write the following in slope-intercept form, then graph it.
-4x + 3y = 6 y +3
+4x x
3y = 4x + 6 +4 4
y = x + 2 3 x

5. Example 3
Write the following in slope-intercept form, then graph it. y
2x + 6y = 3
-2x x
6y = -2x + 3 -2 3
y = x + 6 6 -1 1
y = x + -1 x 3 2 +3 -1
m = 3 1
b = 2

6. Example 4 Write the following in slope-intercept form, then graph it.y
- x + y = 0
+ x x
y = x + 0
b = 0 +1 +1
m = 1 1 x

7. Write the following in slope-intercept form.
1) x + 8y = -8
2) 8x + y = -7
4) 5x + 8y = 64
3) x + 2y = -6

8. Write the following in slope-intercept form.
5) 5x + 6y = -12
6) x + 6y = -42
8) 4x - 7y = -21
7) x - 5y = 0