1. Fun with Functions Katherine Doan 9/22/10

2. The Problem Darby is saving money for her prom dress. If every yard of fabric costs $6.85, how much money will it cost to buy at least 12 yards of fabric?

3. The Equation My equation is: y= 6.85x f(x)= 6.85x y= 6.85x or f(x)= 6.85x X= the number of yards of fabric she buys Y= the total cost of the fabric

4. The Domain and Range Domain – the x values domain ◦My domain is x≥12 Range – the y values range ◦My range is y≥82.2

5. Independent and Dependent depends The total cost of the fabric depends on the number of yards of fabric she buys. Because: independent variable ◦The independent variable is x which is the number of yards of fabric she buys. dependent variable ◦The dependent variable is y which is the total cost of all the fabric. depends ◦y depends on x

6. Function or Not? y You can tell if a relation is a function if every y value has a different x value. x Since all of the x values are different, it is a function.

7. Table of Values x6.85xy(x,y) 126.85(12)82.2(12, 82.2) 136.85(13)89.05(13, 89.05) 146.85(14)95.9(14, 95.9) 156.85(15)102.75(15, 102.75) 166.85(16)109.6(16, 109.6)

8. Prom Dress Graph The total number of yards of fabric Darby buys determines the total cost of the fabric. If she buys 12 yards of fabric it will cost $82.20, but if she buys 16 yards of fabric it will cost $109.60. As the number of yards she buys goes up, the price goes up. Number of yards of fabric Total cost (dollars)

9. Continuous & Discreet My graphed data is continuous. It is continuous because you can purchase one yard, two yards or any number in between. You can have any points in between one and two.

10. In Conclusion: Darby will have to spend at least $82.20 on her dress in order to have the minimum amount of fabric to make a dress. If she wants to add a longer skirt or a sleeve she will need more fabric. I sure hope she can save up all that money in time!