1. SWBAT… Write lines in slope-intercept form Wed, 2/20/10
Agenda
Warm-up (10 min)
Notes on slope intercept – 4 examples (30 min)
Exit slip (5 min)
WARM-UP
HW#3: Writing equations in slope-intercept form

2. Slope-intercept form:
y = mx + b
slope
y-intercept
Now look at the equation below…… 2
What is the slope? ____________ 1
What is the y-intercept? ____________

3. Given y = ½x + ¾, what is the slope and the y-intercept?
m = ½
b = ¾

4. Given y = ½x – ¾, what is the slope and the y-intercept?
m = ½
b = -¾

5. Given y = -½x – ¾, what is the slope and the y-intercept?
m = -½
b = -¾

6. y = mx + b y = mx+ b is an equation that defines a line
A line has two characteristics
1. Slope
2. Points that fall on the line

7. Converting linear equations into Slope-Intercept Form 4 Examples

8. Our main goal is to get the y alone on one side of the equation
Slope intercept form is:
y = mx + b
Our main goal is to get the y alone on one side of the equation

9. Example 1 - convert into slope-intercept form2 1
(divide both sides by 2 to get y alone)
(now simplify all fractions)
Slope (m) = 2
y-intercept (b) = 1

10. *** Your turn – Example 2 – convert into slope-intercept form ***
5y = 10x + 15 2 3
(divide both sides by 5 to get y alone)
(now simplify all fractions)
y = 2x BRAVO!!
Slope (m) = 2
y-intercept (b) = 3

11. *** Your turn – Example 3 – convert into slope-intercept form ***
-3y = -9x – 12
Step 1: divide both sides by -3 to get y alone
Step 2: Simplify all fractions
Step 3: Write your equation in y = mx + b
Slope (m) =
y-intercept (b) =

12. *** Check Your Answer ***
-3y = -9x – 12
(divide both sides by -3 to get y alone)
(now simplify all fractions)
y = 3x + 4
Slope (m) = 3
y-intercept (b) = 4

13. Example 4 - convert into slope-intercept form
21x – 7y = 14
-21x x
(subtract both sides by 21x) 3 2
-7y = -21x + 14
(divide both sides by -7)
(simplify all fractions)
y = 3x – 2
Slope (m) = 3
y-intercept (b) = -2

14. 2y + 26 = -6x ***EXIT SLIP *** Slope (m) = y-intercept (b) =
Step 1: Subtract both sides by 26
Step 2: Divide both sides by 2 to get y by itself
Step 3: Simplify all fractions
Slope (m) =
y-intercept (b) =

15. *** Check Your Answer ***
2y + 26 = -6x
(subtract both sides by 26)
(now divide both sides by 2
2y = -6x – 26
(simplify all fractions)
y = -3x – 13
Slope (m) = -3
y-intercept (b) = -13