Geometry Section 3-4 1112

Preview:

DESCRIPTION

Equations of Lines

Citation preview

SECTION 3-4Equations of Lines

Tuesday, January 3, 2012

ESSENTIAL QUESTIONS

How do you write an equation of a line given information about the graph?

How do you solve problems by writing equations?

Tuesday, January 3, 2012

VOCABULARY

1. Slope-intercept Form:

2. Point-slope form:

Tuesday, January 3, 2012

VOCABULARY

1. Slope-intercept Form: y = mx + b, where m = slope and b = y coordinate of the y-intercept -- (0, b)

2. Point-slope form:

Tuesday, January 3, 2012

VOCABULARY

1. Slope-intercept Form: y = mx + b, where m = slope and b = y coordinate of the y-intercept -- (0, b)

2. Point-slope form: y - y1 = m(x - x1), where m = slope and (x1, y1) is a point on the line

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

a. y =

12

x

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

a. y =

12

x

m =

12

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

a. y =

12

x

m =

12

b = 0

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

a. y =

12

x

m =

12

b = 0y-intercept: (0, 0)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

a. y =

12

x

m =

12

b = 0y-intercept: (0, 0)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

a. y =

12

x

m =

12

b = 0y-intercept: (0, 0)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

a. y =

12

x

m =

12

b = 0y-intercept: (0, 0)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

a. y =

12

x

m =

12

b = 0y-intercept: (0, 0)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

a. y =

12

x

m =

12

b = 0y-intercept: (0, 0)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

a. y =

12

x

m =

12

b = 0y-intercept: (0, 0)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

a. y =

12

x

m =

12

b = 0y-intercept: (0, 0)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

a. y =

12

x

m =

12

b = 0y-intercept: (0, 0)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6 +x

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6 +x +x

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6 +x +x

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6 +x +x

2y = x − 6

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6 +x +x

2y = x − 62 2

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6 +x +x

2y = x − 62 2

y =

12

x − 3

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6 +x +x

2y = x − 62 2

y =

12

x − 3

m =

12

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6 +x +x

2y = x − 62 2

y =

12

x − 3

m =

12

y-intercept = (0, -3)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6 +x +x

2y = x − 62 2

y =

12

x − 3

m =

12

y-intercept = (0, -3)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6 +x +x

2y = x − 62 2

y =

12

x − 3

m =

12

y-intercept = (0, -3)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6 +x +x

2y = x − 62 2

y =

12

x − 3

m =

12

y-intercept = (0, -3)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6 +x +x

2y = x − 62 2

y =

12

x − 3

m =

12

y-intercept = (0, -3)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6 +x +x

2y = x − 62 2

y =

12

x − 3

m =

12

y-intercept = (0, -3)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6 +x +x

2y = x − 62 2

y =

12

x − 3

m =

12

y-intercept = (0, -3)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6 +x +x

2y = x − 62 2

y =

12

x − 3

m =

12

y-intercept = (0, -3)

Tuesday, January 3, 2012

EXAMPLE 1

Identify the slope and y-intercept for each line and graph the lines.

b. 2y − x = −6 +x +x

2y = x − 62 2

y =

12

x − 3

m =

12

y-intercept = (0, -3)

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.

a. m = -2, (0, 4)

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.

a. m = -2, (0, 4)

Use slope-intercept

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.

a. m = -2, (0, 4)

Use slope-intercept

y = mx + b

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.

a. m = -2, (0, 4)

Use slope-intercept

y = mx + b

y = −2x + 4

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.

a. m = -2, (0, 4)

Use slope-intercept

y = mx + b

y = −2x + 4

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.

a. m = -2, (0, 4)

Use slope-intercept

y = mx + b

y = −2x + 4

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.

a. m = -2, (0, 4)

Use slope-intercept

y = mx + b

y = −2x + 4

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.

a. m = -2, (0, 4)

Use slope-intercept

y = mx + b

y = −2x + 4

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.

a. m = -2, (0, 4)

Use slope-intercept

y = mx + b

y = −2x + 4

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.

a. m = -2, (0, 4)

Use slope-intercept

y = mx + b

y = −2x + 4

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.

a. m = -2, (0, 4)

Use slope-intercept

y = mx + b

y = −2x + 4

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.

a. m = -2, (0, 4)

Use slope-intercept

y = mx + b

y = −2x + 4

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.b. m = 3/4, (8, -2)

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.b. m = 3/4, (8, -2)

Use point-slope

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.b. m = 3/4, (8, -2)

Use point-slope

y − y

1= m(x − x

1)

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.b. m = 3/4, (8, -2)

Use point-slope

y − y

1= m(x − x

1)

y + 2 = 3

4(x − 8)

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.b. m = 3/4, (8, -2)

Use point-slope

y − y

1= m(x − x

1)

y + 2 = 3

4(x − 8)

y + 2 = 3

4x − 6

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.b. m = 3/4, (8, -2)

Use point-slope

y − y

1= m(x − x

1)

y + 2 = 3

4(x − 8)

y + 2 = 3

4x − 6

y = 3

4x − 8

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.b. m = 3/4, (8, -2)

Use point-slope

y − y

1= m(x − x

1)

y + 2 = 3

4(x − 8)

y + 2 = 3

4x − 6

y = 3

4x − 8

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.b. m = 3/4, (8, -2)

Use point-slope

y − y

1= m(x − x

1)

y + 2 = 3

4(x − 8)

y + 2 = 3

4x − 6

y = 3

4x − 8

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.b. m = 3/4, (8, -2)

Use point-slope

y − y

1= m(x − x

1)

y + 2 = 3

4(x − 8)

y + 2 = 3

4x − 6

y = 3

4x − 8

Tuesday, January 3, 2012

EXAMPLE 2

Write the equation of the line, choosing which form you would need before you begin. Then

graph the line.b. m = 3/4, (8, -2)

Use point-slope

y − y

1= m(x − x

1)

y + 2 = 3

4(x − 8)

y + 2 = 3

4x − 6

y = 3

4x − 8

Tuesday, January 3, 2012

EXAMPLE 3

Write the equation for the line.

a.

Tuesday, January 3, 2012

EXAMPLE 3

Write the equation for the line.

a.

m = −

57

Tuesday, January 3, 2012

EXAMPLE 3

Write the equation for the line.

a.

m = −

57

(4, -1)

Tuesday, January 3, 2012

EXAMPLE 3

Write the equation for the line.

a.

m = −

57

(4, -1)

y − y

1= m(x − x

1)

Tuesday, January 3, 2012

EXAMPLE 3

Write the equation for the line.

a.

m = −

57

(4, -1)

y − y

1= m(x − x

1)

y +1= − 5

7(x − 4)

Tuesday, January 3, 2012

EXAMPLE 3

Write the equation for the line.

a.

m = −

57

(4, -1)

y − y

1= m(x − x

1)

y +1= − 5

7(x − 4)

y +1= − 5

7x + 20

7

Tuesday, January 3, 2012

EXAMPLE 3

Write the equation for the line.

a.

m = −

57

(4, -1)

y − y

1= m(x − x

1)

y +1= − 5

7(x − 4)

y +1= − 5

7x + 20

7

y = − 5

7x + 13

7

Tuesday, January 3, 2012

EXAMPLE 3

Write the equation for the line.

b.

Tuesday, January 3, 2012

EXAMPLE 3

Write the equation for the line.

b.

m =

68

Tuesday, January 3, 2012

EXAMPLE 3

Write the equation for the line.

b.

m =

68 =

34

Tuesday, January 3, 2012

EXAMPLE 3

Write the equation for the line.

b.

m =

68

(3, 2) =

34

Tuesday, January 3, 2012

EXAMPLE 3

Write the equation for the line.

b.

m =

68

(3, 2)

y − y

1= m(x − x

1)

=

34

Tuesday, January 3, 2012

EXAMPLE 3

Write the equation for the line.

b.

m =

68

(3, 2)

y − y

1= m(x − x

1)

y − 2 = 3

4(x − 3)

=

34

Tuesday, January 3, 2012

EXAMPLE 3

Write the equation for the line.

b.

m =

68

(3, 2)

y − y

1= m(x − x

1)

y − 2 = 3

4(x − 3)

=

34

y − 2 = 3

4x − 9

4

Tuesday, January 3, 2012

EXAMPLE 3

Write the equation for the line.

b.

m =

68

(3, 2)

y − y

1= m(x − x

1)

y − 2 = 3

4(x − 3)

y = 3

4x − 1

4

=

34

y − 2 = 3

4x − 9

4

Tuesday, January 3, 2012

CHECK YOUR UNDERSTANDING

Review problems #1-12 on p. 200

Tuesday, January 3, 2012

PROBLEM SET

Tuesday, January 3, 2012

PROBLEM SET

p. 200 #13-41 odd, 55

“We can have facts without thinking, but we cannot have thinking without facts.” - John Dewey

Tuesday, January 3, 2012