Warm-Up

Evaluate for x = -1, 0, and 2.

1. f(x) = 3x – 7

2. f(x) = -2x + 12

5.1

Objectives:1. Write linear equations given m and b.2. Use linear equations in real life.

 

Vocabulary: Slope-intercept Form

Writing Linear Equations in Slope-Intercept Form

5.1

Slope-intercept Form:

m = b =

y = mx + b

Writing Linear Equations in Slope-Intercept Form

5.1

slope of a line =

y- intercept (0, b)

riserun

Reviewing Chapter 4

Find the slope and y-intercept of these:

y = 2x + 5

m = b =

Reviewing Chapter 4

Find the slope and y-intercept of these:

y = -x – 3

m = b =

Reviewing Chapter 4

Find the slope and y-intercept of these:

y = 4

m = b =

What kind of line is

this?

Reviewing Chapter 4

Find the slope and y-intercept of these:

y = ½x + 4

m = b =

Reviewing Chapter 4

Find the slope and y-intercept of these:

y = 3 – 7x

m = b =

y = mx + b

Writing Linear Equations in Slope-Intercept Form

5.1

How to find the equation of a line:

1. Find the slope (m) of the line.2. Find the y-intercept (b) of the line.3. Plug these values into y = mx + b

m = 4 b = 3

y = 4x + 3

Example 1 Writing an Equation of a Line

Write the equation of the line whose slope m = -2 and whose y-intercept b = 5.

y = mx + b

Example 1 Writing an Equation of a Line

Write the equation of the line whose slope and whose y-intercept .

y = mx + b

2m

3 b 2

Example 1 Writing an Equation of a Line

Write the equation of the line whose slope and whose y-intercept .

y = mx + b

4m

5 (0, 4)

Example 1 Writing an Equation of a Line

Write the equation of the line whose slope m = 1 and whose y-intercept b = 7.

y = mx + b

Example 2 Writing an Equation of a Line from a Graph

Write the equation of the line shown in the graph.

1 2 3 4 5 6 7

123

56

4

7

-6

-2

-4

-6-4 -2y = mx + b

Purple:

Blue:

Pink:

Orange:

Example 3 A Linear Model for Population

The number of trout in a lake was estimated to be 44.5 thousand in 1995. During the next 10 years, the trout population is expected to increase by about 3.2 thousand per year. Write a linear equation to model the trout population in any year between 1995 and 2005. Let t be the number of years since 1995.

Predict the trout population in 2002.

P = 3.2t + 44.5

≈ 66.9 thousand trout

Guided Practice

Please complete #3-11 on pg. 276 in your textbook. Raise your hand when you are done.

3. 9.

4. 10.

5.

6.

7.

8. 11.

5.1

To be turned in for a classwork grade!

Tonight’s Homework

pg. 276#’s 12-19 all, 21-29 odd