SECTION 3.1 Functions
 Expressing a Function
 SECTION 3.1 EXERCISES
 SKILLS
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 APPLICATIONS
 101 Budget: Event Planning. The cost associated with a catered wedding reception is
 102 Budget: Long-Distance Calling. The cost of a local home phone plan is
 103 Temperature. The average temperature in Tampa, Florida, in the springtime is given by the function
 104 Falling Objects: Firecrackers. A firecracker is launched straight up, and its height is a function of time,
 105 Collectibles. The price of a signed Alex Rodriguez baseball card is a function of how many are for sale. When Rodriguez was traded from the Texas Rangers to the New York Yankees in 2004, the going rate for a signed baseball card on eBay was
 106 Collectibles. In Exercise 105, what was the lowest price on eBay, and how many cards were available then? What was the highest price on eBay, and how many cards were available then?
 107 Volume. An open box is constructed from a square 10-inch piece of cardboard by cutting squares of length
 108 Volume. A cylindrical water basin will be built to harvest rainwater. The basin is limited in that the largest radius it can have is Hint:
 109 Economics. Approximate the exchange rates of the U.S. dollar to the nearest yen during Weeks 4, 7, and 8.
 110 Economics. Find the increase or decrease in the number of Japanese yen to the U.S. dollar exchange rate, to the nearest yen, from (a) Week 2 to Week 3 and (b) Week 6 to Week 7.
 111 Medicine/Health. How many people have contracted malaria 14 days into the outbreak?
 112 Medicine/Health. How many people have contracted malaria 6 days into the outbreak?
 113 Environment: Tossing the Envelopes. The average American adult receives 24 pieces of mail per week, usually of some combination of ads and envelopes with windows. Suppose each of these adults throws away a dozen envelopes per week.
 114 Environment: Tossing the Envelopes. Each month, Jack receives his bank statement in a 9.5 inch by 6 inch envelope. Each month, he throws away the envelope after removing the statement.
 115 Finance. Is the relation whose domain is the year and whose range is the average federal funds rate for the month of January a function? Explain.
 116 Finance. Write five ordered pairs whose domain is the set of even years from 2000 to 2008 and whose range is the set of corresponding average federal funds rate for the month of January.
 117 Health Care Costs. Fill in the following table. Round dollars to the nearest Write the five ordered pairs resulting from the table.
 118 Health Care Costs. Using the table found in Exercise 117, let the years correspond to the domain and the total costs correspond to the range. Is this relation a function? Explain.
 119 Environment: Global Climate Change. Estimate (to the nearest thousand) the value of
 120 Environment: Global Climate Change. Explain what the sum
 CATCH THE MISTAKE
 121 Determine whether the relationship is a function. Solution: Apply the horizontal line test. Because the horizontal line intersects the graph in two places, this is not a function. This is incorrect. What mistake was made?
 122 Given the function Solution: This is incorrect. What mistake was made?
 123 Given the function Solution: This is incorrect. What mistake was made?
 124 Determine the domain of the function Solution: What can This is incorrect. What mistake was made?
 125 Given the function Solution:
 126 Given the functions Solution: The absolute value of zero is zero, so there is no need for the absolute value signs: This is incorrect. What mistake was made?
 CONCEPTUAL
 127 If a vertical line does not intersect the graph of an equation, then that equation does not represent a function.
 128 If a horizontal line intersects a graph of an equation more than once, the equation does not represent a function.
 129 If
 130 If
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 132 If
 CHALLENGE
 133 If
 134 Construct a function that is undefined at
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 TECHNOLOGY
 137 Using a graphing utility, graph the temperature function in Exercise 103. What time of day is it the warmest? What is the temperature? Looking at this function, explain why this model for Tampa, Florida, is valid only from sunrise to sunset (6 to 18).
 138 Using a graphing utility, graph the height of the firecracker in Exercise 104. How long after liftoff is the firecracker airborne? What is the maximum height that the firecracker attains? Explain why this height model is valid only for the first 8 seconds.
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 140 The makers of malted milk balls are considering increasing the size of the spherical treats. The thin chocolate coating on a malted milk ball can be approximated by the surface area,
 141 Let
 142 Let