1. P.2 Linear Models and Rates of Change

2. Objectives  Find the slope of a line passing through two points.  Write the equation of a line with a given point and slope.  Interpret slope as a ratio or as a rate in a real-life application.  Write equations of lines that are parallel or perpendicular to a given line.

3. Slope of a Line  slope rise / run ∆y / ∆x change in y / change in x

4. Slope positivenegative zerono slope

5. Point-Slope Equation

6. Slope-Intercept Form

7. Example Find the equation of a line that has slope 3 and passes through (1, -2).

8. Parallel and Perpendicular Lines  Two distinct non-vertical lines are parallel iff their slopes are equal.  Two distinct non-vertical lines are perpendicular iff m 1 =-1 / m 2.

9. Example Find the equation of a line that is parallel to 2x-3y=5 and passes through (2,-1).

10. Example Find the equation of a line that is perpendicular to 2x-3y=5 and passes through (2,-1).

11. Technology Tip  Unless you have equal x and y scaling, graphs on the calculator many not appear to be perpendicular when they really are.  Try: y= 2/3 x – 5/3 Zoom 6 Zoom 5

12. P.4 Fitting Models to Data  Look at page 0: Eruptions of Old Faithful.

13. Homework P.2: page 16 #1-5 odd 23-39 odd 59-65 odd (Don't sketch graphs and don't use the standard form of a line.)