MAT 150 Unit 2-4 Part 1: Quadratic Models
Objectives Find the exact quadratic function that fits three points on a parabola Model data approximately using quadratic functions
Example 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. Solution
Example (cont) Solution A parabola passes through the points (0, 5), (4, 13), and (–2, 25). Write the equation of the quadratic function whose graph is a parabola. Solution
Example A parabola passes through the points (0, 5), (4, 13), and (–2, 25). Write the equation of the quadratic function whose graph is a parabola. Solution
Example The table shows the dollar value or projected dollar value of the U.S. mobile Internet advertising market for the years from 2006 to 2012.
Example (cont) a. Create a scatter plot of the data with x equal to the number of years after 2000. Solution
Example (cont) b. Find the quadratic function that is the best fit for the data, with x equal to the number of years after 2000. Solution
Example (cont) c. Graph the aligned data and the model on the same axes. Does this model seem like a reasonable fit? Solution
Example (cont) d. Use the model to find the year in which the mobile Internet advertising market is projected to reach $3 billion. Solution
Example The table gives the number of Starbucks stores in the United States for the years 1992 through 2009
Example (cont) a. Create a scatter plot of the data points with x equal to the number of years after 1990. Solution
Example (cont) b. Create a quadratic function that models the data, using the number of years after 1990 as the input x. Solution
Example (cont) c. Graph the aligned data and the quadratic function on the same axes. Does the model seem like a reasonable fit? Solution
Example (cont) d. Use the model to estimate the number of stores in 2008. Discuss the reliability of this estimate. Solution
Example (cont) Use the model to estimate the number of stores in 2012. Discuss the reliability of this estimate. Solution