Warm ups1. Find the x and y intercepts: 3x -9y = 18

2. Write in Point-Slope Form:

(5,-3) m = -2 (3,4) (-1,8)

3. Write in Standard Form:

(2,3) (0,3) (4, -5) m = -3

(6,0)(0, 2)

3 2( 5)y x

4 1( 3)

8 1( 1)

y x

or

y x

3y 3 7x y

Reminders

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6-4 Slope-Intercept Form

Objective: To write an equation in slope-intercept form.

Slope-Intercept Form

Does anyone know what it is?...

y = mx + b

m = slopeb = y-intercept (this is on y axis)

Given slope and y-intercept

Example 1: Write an equation in slope-intercept form

Given: m = 4 b = -2

y = 4x – 2

Example 2: Write an equation in slope-intercept form

Given:

35

2y x

3, 52

m b

Write in Slope-Intercept

5x – 4y = 202

3 ( 3)3

y x 5x 5x

4 5 20y x

4 4 4

55

4y x

23 2

3y x 3 3

25

3y x

Example 5

Write an equation in slope-intercept form given:

(2,1) (4,0)

Steps:

1. Find slope

2. Plug into point-slope

3. Convert to slope-intercept

x1 y1 x2 y2

0 1

4 2m

1

2

10 ( 4)

2y x

12

2y x

Example 6

Write an equation in slope-intercept form given:

(0,6) (4,0) x1 y1 x2 y2

0 6

4 0m

6

4

3

2

36 ( 0)

2y x

36

2y x

36

2y x

Given a graph

Example 7: write an equation in slope-intercept form

b = 2

m = -2/3

-2

32

23

y x

Given a graph

TOO: write an equation in slope-intercept form

b = -4 m = 1

11

y = x – 4

TOO – students can present.

1. m = 5, b = -3

2. y – 2 = 4(x + 7)

3. (-2,-3) (-1,2)

Answers:

1. y = 5x – 3

2. y = 4x + 30

3. y = 5x + 7

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Homework

Slope-Intercept Form Practice

Math Lab Warm ups1. Find the x and y intercepts: 6x - 2y = 24

2. Write in Point-Slope Form:

(2,-1) m = -5 (6,-2) (0,5)

3. Write in Standard Form:

(0,7) (1,2) (5, 9) m = 3