1.4 Linear Functions
September 25, 2008
1.4 ­ Linear Functions
Objective:
• You will be able to graph linear functions that are written in slope­intercept form and standard form.
• You will be able to write the equation of a line given specific properties..
• Graphing lines written in standard form using the intercepts.
• Use linear functions to solve problems.
Sep 15 ­ 9:05 AM
1
1.4 Linear Functions
September 25, 2008
Given the line:
• find the slope
•
write the equation of the line
Jun 3 ­ 9:07 AM
2
1.4 Linear Functions
September 25, 2008
Writing equations of lines.
Point­Slope Formula
1. Write the equation of the line given m = ­2 and the point (­2, 3). Sep 15 ­ 9:12 AM
3
1.4 Linear Functions
September 25, 2008
Writing equations of lines.
Point­Slope Formula
2. Write the equation of the line given (2, 3) and the point (­4, 5). Sep 15 ­ 9:12 AM
4
1.4 Linear Functions
September 25, 2008
Writing equations of lines.
Point­Slope Formula
3. Find the equation of the line that contains the point
(1, ­2) and is perpendicular to the line x + 2y = 6.
Sep 15 ­ 9:12 AM
5
1.4 Linear Functions
September 25, 2008
Writing equations of lines.
Point­Slope Formula
4. Find the equation of the line that contains the point
(2, ­3) and is parallel to the line 2x + y = 6.
Sep 15 ­ 9:12 AM
6
1.4 Linear Functions
September 25, 2008
Show that the two lines are parallel.
2x + 3y = 6
4x + 6y = 0
Sep 18 ­ 1:56 PM
7
1.4 Linear Functions
September 25, 2008
Point­Slope Formula
Slope intercept form
y = mx + b
Standard Form
Ax + By = C
Sep 24­4:07 PM
8
1.4 Linear Functions
September 25, 2008
1. Find the intercepts of the graph and then graph the line.
2x + 4y = 8
Jun 3 ­ 9:37 AM
9
1.4 Linear Functions
September 25, 2008
Application problem
Commonwealth Edison Company supplies electricity to residential customers for a monthly charge of $7.58 plus 8.275 cents per kilowatt­hour for up to 400 kilowatt­hours.
1. Identify the variables. State the domain of the function.
2. Write an equation that relates the monthly charge, in dollars,
to the number of kilowatt­hours used in a month. 3. What is the monthly charge for using 100 kilowatt­hours?
4. What is the charge for using 300 kilowatt­hours?
5. Describe what the y­intercept represents and what the slope represents.
Sep 18 ­ 2:07 PM
10
1.4 Linear Functions
September 25, 2008
Homework
pg. 41­ 44 #'s: 33­40, 42­64 even, 86­96 even, 97­100, 105, 109, 118, 120
You ROCK!
Sep 18 ­ 2:15 PM
11