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messersmith_power_intermediate_algebra_1e_ch4_7_10

b) To determine how much sound is read after 1.5 min, do we let t 1.5 and fi nd S(1.5)? No. Recall that t is in seconds. Change 1.5 min to seconds before substituting for t. We must use the correct units in the function. 1.5 min 90 sec Let t 90 and fi nd S(90). S(t) 44.1t S(90) 44.1(90) S(90) 3969 S(t) is in thousands, so the number of samples read is 3969 1000 3,969,000 samples of sound. c) Since we are asked to determine how long it would take a CD player to scan 1,764,000 samples of sound, we will be solving for t. What do we substitute for S(t)? S(t) is in thousands, so substitute 1,764,000 1000 1764 for S(t). Find t when S(t) 1764. S(t) 44.1t 1764 44.1t Substitute 1764 for S(t). 40 t Divide by 44.1. It will take 40 sec for the CD player to scan 1,764,000 samples of sound. d) Since t represents the number of seconds a CD has been playing, the smallest value that makes sense for t is 0. e) Since S(t) is in thousands of samples, the information we obtained in parts a), b), and c) can be written as the ordered pairs (20, 882), (90, 3969), and (40, 1764). In addition, when t 0 (from part d) we obtain S(0) 44.1(0) 0. (0, 0) is an additional ordered pair on the graph of the function. Number of Samples of Sound Scanned by a CD Player in t sec S(t) 44.1 t (90, 3969) (40, 1764) (20, 882) t S(t) 100 0 20 60 140 Number of seconds Number of samples of sound (in thousands) 5000 4500 4000 3500 3000 2500 2000 1500 1000 500 ANSWERS TO YOU TRY EXERCISES 1) a) domain: {1, 1, 2, 4}; range: {3, 1, 3, 7}; yes b) domain: {12, 1, 0}; range: {6, 6, 13, 0}; no c) domain: {Daisy, Tulip, Dog, Oak}; range: {Flower, Animal, Tree}; yes 2) a) function; domain: (q, q); range: (q, q) b) not a function; domain: 4, q); range: (q, q) 3) a) yes b) no 4) a) (q, q); function b) (q, q); function c) (q, 1) ´ (1, q); function 5) a) 2 b) 2 6) a) 19 b) 9 c) 7 d) 20 7) a) 3 b) 5 c) 1 8) a) f (k) 2k 7 b) f (p 3) 2p 1 9) m 3 4 , y-int: (0, 2) x y 5 f(x) x 2 34 (4, 1) 5 5 5 (0, 2) 208 CHAPTER 4 Linear Equations in Two Variables and Functions www.mhhe.com/messersmith


messersmith_power_intermediate_algebra_1e_ch4_7_10
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