SWBAT… Write lines in slope-intercept form Mon, 11/28 Agenda1. WU (10 min)2. Slope quiz review (5 min)3. 5 Practice problems - slope-intercept form (20 min)

Warm-Up1. Find the slope of (6c, 2d) and (8c, 4d)2. The table shows production costs for building

different numbers of skateboards. Determine the missing value, x, that will result in a linear model.

HW4: Writing Equations in slope-intercept form

Skateboards Built Production Costs ($)

14 32528 500x 375

22 425

Find the slope of (6c, 2d) and (8c, 4d)

12

12

xx

yym

cc

ddm

68

24

c

dm

2

2

c

dm

The table shows production costs for building different numbers of skateboards. Determine the missing value, x, that will result in a linear model.

Skateboards Built Production Costs ($)

14 32528 500x 37522 425

1428

325500

12

12

xx

yym

When an equation is in slope-intercept When an equation is in slope-intercept form:form:

When an equation is in slope-intercept When an equation is in slope-intercept form:form:

What is the slope? ____________

2 1y x Now look at the equation below……

What is the y-intercept? ____________

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

m = ½b = ¾

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

m = ½b = -¾

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

m = -½b = -¾

• y = mx+ b is an equation that defines a line

• A line has two characteristics• Slope• Points that fall on the line (the y-intercept is on the

line)

Converting linear equations Converting linear equations into Slope-Intercept Form, into Slope-Intercept Form,

yy = = mxmx + + bb

Converting linear equations Converting linear equations into Slope-Intercept Form, into Slope-Intercept Form,

yy = = mxmx + + bb

Our main goal is to get the Our main goal is to get the yy alonealone on one side of the equation on one side of the equation

6 Examples6 Examples

Example 1 - convert into Slope-Intercept Form

Example 1 - convert into Slope-Intercept Form

2 4 2y x 2 2

2 4 2y x 2 2 2

(divide both sides by 2 to get y alone)

2 4 2y x

(now simplify all fractions)2 1

2 1y x What is the slope? _____ What is the y-intercept? ______

Example 2 – Convert to Slope-Intercept Form

-3y = -9x – 12Step 1: Divide both sides by -3 to get y alone

Step 2: Simplify all fractions

Step 3: Write your equation in y = mx + b

What is the slope? ____________

What is the y-intercept? ____________

*** Check Your Answer ***

-3y = -9x – 12 (divide both sides by -3 to get y alone)

(now simplify all fractions)

y = 3x + 4

-3 -3

-3y = -9x – 12-3 -3 -3

Slope = 3

Intercept = 4

Wow, you’re good at this!!

Example 3: Convert to Slope-Intercept Form

21x – 7y =14 (subtract both sides by 21x)

-7y = -21x + 14(now divide both sides by -7)

y = 3x – 2

(simplify all fractions)

21 -21xx

7 - 7 -7

What is the slope? _________

What is the y-intercept? ________

2y + 26 = -6x

Step 1: Subtract both sides by 26

Step 2: Divide both sides by 2 to get y by itself

Step 3: Simplify all fractions

Example 4: Convert to Slope-Intercept Form

What is the slope? ____________

What is the y-intercept? ____________

2y + 26 = -6x(subtract both sides by 26)

2y = -6x – 26(now divide both sides by 2

y = -3x – 13

(simplify all fractions)

You are a math wizard!

*** Check Your Answer ***

26 -26

2 2 2

Example 5: In the standard (x, y) coordinate plane, what is the slope of the line given by the equation 5x – 4y = 3?

Example 6: In the standard (x, y) coordinate plane, what is the slope of the line given by the equation 4y = 24?

Video: Families of Linear Graphs

• http://www.glencoe.com/sites/texas/student/mathematics/assets/animation/algebra1/ALG1CIM4-3.swf