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messersmith_power_intermediate_algebra_1e_ch4_7_10

Solution a) Because x is the number of years after 2000, the year 2002 corresponds to x 2. y 16.4x2 50.6x 896 y 16.4(2)2 50.6(2) 896 Substitute 2 for x. y 860.4 The total tourism-related output in 2002 was approximately $860.4 billion. b) Because y represents the total tourism-related output (in billions), substitute 955 for y and solve for x. y 16.4x2 50.6x 896 955 16.4x2 50.6x 896 Substitute 955 for y. 0 16.4x2 50.6x 59 Write in standard form. Use the quadratic formula to solve for x. a 16.4  b 50.6  c 59 x 50.6 2(50.6)2 4(16.4)(59) 2(16.4) x 3.99 4 or x 0.90 Substitute the values into the quadratic formula. The negative value of x does not make sense in the context of the problem. Use x 4, which corresponds to the year 2004. The total tourism-related output was about $955 billion in 2004. ANSWERS TO YOU TRY EXERCISES 1) m 2E v 2 2) a) e5 137 6 , 5 137 6 f b) e p 2p2 12r 6 , p 2p2 12r 6 f 3) length 20 in., width 18 in. 4) 2 ft Think carefully about how to relate the information given to the variables in the equation. 10.4 Exercises Do the exercises, and check your work. Objective 1: Solve a Formula for a Variable Solve for the indicated variable. 1) A pr2 for r 2) V 1 3 pr2h for r 3) a v2 r for v 4) K 1 2 Iw2 for w 5) E I d2 for d 6) L 2U I 2 for I 7) F kq1q2 r 2 for r 8) E kq r2 for r 9) d A 4A p for A 10) d A 12V ph for V 11) Tp 2p A l g for l 12) V A 3RT M for T 13) Tp 2p A l g for g 14) V A 3RT M for M 15) Compare the equations 3x2 5x 4 0 and rx2 5x s 0. a) How are the equations alike? b) How can both equations be solved for x? 16) What method could be used to solve 2t2 7t 1 0 and kt2 mt n 0 for t? Why? Solve for the indicated variable. 17) rx2 5x s 0 for x 18) cx2 dx 3 0 for x 19) pz2 rz q 0 for z 20) hr2 kr j 0 for r 650 CHAPTER 10 Quadratic Equations and Functions www.mhhe.com/messersmith


messersmith_power_intermediate_algebra_1e_ch4_7_10
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