1. Unit 2 – Linear Equations & Inequalities
Topic: Writing & Graphing Linear Functions
Materials needed for notes: Pencil & paper
Flip book
Journal

2. Things I expect you to remember from Algebra 1 that I do not explain in this PowerPoint
Slope-intercept form of a linear equation.
Graphing a linear function given:
A point on the line & the slope of the line.
The function of the line in slope-intercept form.
Using the slope formula (I will give you the formula in a couple slides, but I expect you to remember how to use it).
Using the graph of a line to write a function in slope-intercept form.

3. Things you should remember from Algebra 1 but that I KNOW you need to be reminded of
Identifying a linear function from data.
Standard form of a linear equation.
Recognizing standard form & graphing a line given a function in standard form.
The equations for horizontal & vertical lines.
Using data to write a linear function in slope-intercept form.
The relationship in the slopes of parallel & perpendicular lines.

4. Formulas for Linear Functions (put these on a note card)
Slope formula
(x1, y1) & (x2, y2) are coordinates for 2 points on the line
Standard form of a linear function
A, B, C  R, A & B cannot both be 0
Point-slope form of a linear function
x1, y1 represent the coordinates of a point on the line
Can be used to find the equation of a line in slope-intercept given slope & a point, or two points

5. Identifying Linear Functions From Data
Linear functions have one & only one output value for every input value.
Rate of change (slope) between dependent variable and independent variable is constant.

6. Identifying Linear Functions From Data+2 +2 +2 x 2 4 6
f(x) -1 8 17 +3 +6 +9
Rate of change is not constant. Data represents a function, but not a linear function.

7. Identifying Linear Functions From Data+2 +2 +2 x -2 2 4
f(x) 3 +0 +0 +0
Rate of change is constant. Data represents a linear function.

8. Identifying Linear Functions From Datax -3 -1 1
f(x) 3 -6
Two different outputs for the same input. Data does not represent a function.

9. Graphing Linear Functions in Standard Form
Use standard form to determine x- & y-intercepts.
Set y = 0 & solve for x to find x-intercept.
Set x = 0 & solve for y to find y-intercept.
Plot the intercepts and graph the line they form.

10. Horizontal & Vertical Lines
Horizontal lines have m = 0
No rise, just run
y-value is constant so equation is always y = b, where b = y-intercept
Example: write the equation for the given line
y = 5

11. Horizontal & Vertical Lines
Vertical lines have undefined slope
Rise, but no run (can’t divide by 0)
x-value is constant so equation is always x = a, where a = x-intercept
Example: write the equation for the given line
x = –7

12. Parallel & Perpendicular Lines
Parallel Lines
Two lines whose slopes are equal.
Perpendicular Lines
Two lines whose slopes are negative reciprocals.
The product of the slopes of perpendicular lines is -1.
EXCEPTION: A horizontal line (m = 0) is perpendicular to a vertical line (m is undefined).

13. JOURNAL ENTRY
TITLE: Checking My Understanding: Writing & Graphing Linear Functions
Review your notes from this presentation & create and complete the following subheadings:
“Things I already knew:” Identify any information with which you were already familiar.
“New things I learned:” Identify any new information that you now understand.
“Questions I still have:” What do you still want to know or do not fully understand?

14. Homework Textbook Section 2-3 (pg. 110): 22-40 even
Due 9/6 (B day) or 9/7 (A day)