1. MAT 150 – Algebra Class #11 Topics:
Find the exact quadratic function that fits three points on a parabola
Model data approximately using quadratic functions

2. Writing a Quadratic Function
A parabola passes through the points (0, 5), (4, 13) and (-2, 25). Write the equation of the quadratic function whose graph is this parabola.

3. Speed vs. Fuel Economy
A study compared the speed x (in miles per hour) and the average fuel economy y (in miles per gallon) for cars. The results are shown in the table. Using the function, what is the fuel economy if the speed is 47?
Plot the data points. Is it linear or quadratic?
Write the equation of this function.
Speed, x
Fuel Economy, y 15
22.3 20
25.5 25
27.5 30 29 35
28.8 40 45
29.9 50
30.2 55
30.4 60 65
27.4 70
25.3
(Source: Transportation Energy Data Book)

4. Quadratic Regression
Using the pervious data, put the data into your calculator where Speed is List 1 and Fuel Economy is List 2 Now select STAT, CALC, 5: QuadReg What is the fuel economy if the speed is 47? When can we be certain that this model no longer applies?

5. How to use Excel

6. Modeling with Power Functions
Years after 1950
Households (thousands) 10
439 20
523 30
1589 35
1983 40
2856 45
3668 52
4898 54
5080 57
6209 58
6210
Plot the data points.
Write the equation of this function.

8. How to use Excel

9. Assignment
Pg #1 , 5 and 8 #12, 15, 17, 20, 21 #29, 35, 45, 48