1. Notes P.4 – Lines in the Plane

2. I. Slope:
Def. – The slope of a nonvertical line through the points (x1, y1) and (x2, y2) is
If the line is vertical, the slope is undefined.

3. II. Forms of Linear Equations:
A. Point-Slope Form:
B. Slope-Intercept Form:
C.) General Form:

4. D. Vertical Line:
E. Horizontal Line:

5. III. Linear Regression:
A. Def. – The process of using data to determine a linear model or relationship between two variable quantities.
B. Ex. – Determine the linear relationship between Fahrenheit and Celsius temperature. Then, find the Celsius equivalent of 90̊ F and the Fahrenheit equivalent of -5 ̊ C.

6. Solution:
First, we provide ourselves with a linear equation to model the relationship of
Now, use the fact that water boils at 100̊ C and 212 ̊ F and freezes at 0 ̊ C and 32 ̊ F to set up a system of two equations and two variables.

7. Solution cont.: Solving the second equation leaves us with
Using substitution, we find that
Therefore,

8. Solution cont.:
When F =90 ̊ ,
When C =-5 ̊ ,

9. IV. Linear Regression with TI-83+
A. Enter the following data on your calculator and follow along with the TI-83+ overhead.

10. World Population in millions:
Year
Population
1980
4454
1985
4853
1990
5285
1995
5696
2003
6305
2004
6378
2005
6450

12. V. Quick Review
Complete the in-class worksheet.

13. Homework: p.36 #5,9,13,17,21,25,29,35,43,47,51,55,59,61-68