1. HW: Get Ready for Chapter 4 (back of agenda)
Mon, 11/26 SWBAT… graph families of linear functions on a TI-83 graphing calculator
Agenda
WU - (10 min)
Graphing calculator activity (35 min)
Warm-Up:
Write your HW in your planner for the week.
Review your test corrections and your updated grade on the top right of your test in red.
HW: Get Ready for Chapter 4 (back of agenda) 1

2. We have begun a new unit on graphs and linear functions:
Students will be able to:
Write and interpret x-and y-intercepts (HW1 / HW2)
Graph lines using x-and y-intercepts (HW1 / HW2)
Calculate and interpret slope (HW3)
Graph lines in slope-intercept form (HW4)
Write equations in slope-intercept form (HW4 / HW6)
Write equations in point-slope form (HW5)
Write equations in standard from (HW5)
Determine lines of best fit (HW7)
Write equations that are parallel or perpendicular (HW8)
Unit test after Winter break on 1/17/13!
Final exam during the week of 1/28/13!

3. Today, you will be using the TI-83 graphing calculators to graph families of linear functions
Your goal is to make conclusions on some characteristics of linear functions and to remember slope and y-intercept.
Keep in mind the parent linear function, y = x

4. SWBAT… find x- and y-intercepts graphically and algebraically
Wed, 11/28
SWBAT… find x- and y-intercepts graphically and algebraically
Agenda
Warm-Up (10 min)
Notes on x- and y intercepts (15 min)
OYO problems (10 min)
Warm-Up:
1. Graph y – 1 = 2x using a table of values
2. Circle and label the point where the line crosses the x-axis
3. Circle and label the point where the line crosses the y-axis
HW#1: x- and y-intercepts
Solve for y (add 1 to both sides)
y = 2x + 1

5. What does it mean to INTERCEPT a pass in football?
The path of the defender crosses the path of the thrown football.

6. x- and y-intercepts
The x-intercept of a line is the point at which the line crosses the x-axis. ( i.e. where the y value equals 0 ) x-intercept = ( x, 0 )
The y-intercept of a line is the point at which the line crosses the y-axis. ( i.e. where the x value equals 0 ) y-intercept = ( 0, y )

7. Directions: Find the x- and y-intercepts Ex1: y = 2x + 1
x-int. y = 0
y = 2x + 1
0 = 2x + 1
-2x = 1
x = -1/2
(-1/2, 0)
y-int. x = 0
y = 2x + 1
y = 2(0) + 1
y = 1
(0, 1)

8. Now go back and look at your WU line
Q: What was the x-intercept graphically?
A: (-1/2, 0)
Q: What was the x-intercept algebraically?
Q: What was the y-intercept graphically?
A: (0, 1)
Q: What was the y-intercept algebraically?

9. What are the x- and y-intercepts?
(2, 0) x
The x-intercept is where the graph crosses the x-axis.
The y-coordinate is always 0.
The y-intercept is where the graph crosses the y-axis.
The x-coordinate is always 0.
(0, -6)

10. Directions: Find the x- and y-intercepts Ex2: -3x + 5y = 9
x-int. y = 0
-3x + 5y = 9
-3x + 5(0) = 9
-3x = 9
x = -3; (-3, 0)
y-int. x = 0
-3(0) + 5y = 9
5y = 9
y = ; (0, )

11. Graphing linear equations
To graph a linear equation you can use:
1.) Table of values (last week)
2.) Intercepts (right now!)
3.) Slope intercept form (y = mx + b) (next project)

12. Graph y = 2x + 1 using x- and y- intercepts
To graph lines using x- and y-intercepts:
Step 1: Find the x- and y-intercepts.
x-int: (-1/2, 0)
y-int: (0, 1)
Step 2: Plot the two points.
Step 3: Connect the points, extend the line, arrows at end, label the line.

13. Find the x- and y-intercepts Ex3: y = 3 ***Special case***
x-int. Let y = 0
y = 3
0 = 3
0 = 3???
No! There is no x-intercept. None
What type of lines have no x-intercept?
Horizontal!
y-int. Let x = 0
y = 3 (y is already solve for)
(0, 3) x
y = 3

14. Find the x- and y-intercepts Ex4: x = -4 ***Special case***
x-int. Let y = 0
x = -4 (x is already solved for)
(-4, 0)
y-int. Let x = 0
x = -4
0 = -4???
No, there is no y-intercept. None
What type of lines have no y-intercept?
Vertical!
x = -4

15. Interpreting x-and y-intercepts: Swimming Pool
x-int: (14, 0): After 14 hours, the water has a volume of 0 gallons, or the pool is completely drained.
y-int: (0, 10,080): The pool contained 10,080 gallons of water at time 0, or before it started to drain.
Draining a Pool
Time (h) x
Volume (gal) y
10,080 2
8,640 6
5,760 10
2,880 12
1,440 14

16. SWBAT… find x- and y-intercepts graphically and algebraically
Fri, 11/30
SWBAT… find x- and y-intercepts graphically and algebraically
Agenda
Warm-Up (5 min)
5 MC examples (10 min)
Review HW#3 (10 min)
x- and y-intercepts interpretation (20 min)
Warm-Up:
1. Which is the best estimate for the x-intercept of the graph of the linear function
A. Between 0 and 1
B. Between 2 and 3
C. Between 1 and 2
D. Between 3 and 4
HW#4: x- and y-intercepts x y 5 1 3 2 -1 4 -3

17. What is the x-intercept of 3x – 4y = 24?
(-6, 0)
(8, 0)
(0, -4)
(8, -6) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

18. What is the y-intercept of -x + 2y = 8?
(-1, 0)
(-8, 0)
(0, 2)
(0, 4)
Solve for y: Ax + By = C 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

19. What is the x-intercept of y = 1? (Hint: Draw this graph)
(1, 0)
(-1, 0)
(0, 1)
None x 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

20. What is the y-intercept of y = 1? (Hint: Draw this graph)
(1, 0)
(-1, 0)
(0, 1)
None x 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

21. What is the y-intercept of x = 3? (Hint: Draw this graph)
(3, 0)
(-3, 0)
(0, 3)
None x 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

22. HW#4 Answers x-int = (3, 0) y-int = (0, 5) x-int = (7, 0)