c) When the ball hits the ground, how high off the ground is it? It is 0 feet high. Find t when h 0. h 16t2 32t 20 0 16t2 32t 20 Substitute 0 for h. 0 4t2 8t 5 Divide by 4. 0 (2t 1)(2t 5) Factor. b R 2t 1 0 or 2t 5 0 Set each factor equal to 0. 2t 1 2t 5 t 1 2 or t 5 2 Solve. Since t represents time, t cannot equal 1 2 . Therefore, t ANSWERS TO YOU TRY EXERCISES 1) base 7 cm; height 10 cm 2) 13, 15, 17 or 3, 1, 1 3) 3 4) length of wire 17 ft; height of pole 15 ft 5) a) 36 ft b) 0.25 sec and 2 sec c) 3 sec 5 2 . The ball will hit the ground after 5 2 sec (or 2.5 sec). Fill in your picture with the information you found by completing the example. Did it make sense? YOU TRY 5 An object is thrown upward from a building. The height h of the object (in feet) t sec after the object is released is given by the quadratic equation h 16t2 36t 36 a) What is the initial height of the object? b) How long does it take the object to reach a height of 44 ft? c) How long does it take for the object to hit the ground? 7.6 Exercises Do the exercises, and check your work. Objective 1: Solve Problems Involving Geometry Find the length and width of each rectangle. 1) Area 28 in2 x x 3 2) Area 96 cm2 x 3 x 1 length 7 in.; width 4 in. length 12 cm; width 8 cm Find the base and height of each triangle. 3) Area 44 cm2 x 3 2x 4) Area 12 ft2 x 5 base 11 cm; height 8 cm x 23 base 4 ft; height 6 ft *Additional answers can be found in the Answers to Exercises appendix. 438 CHAPTER 7 Factoring Polynomials www.mhhe.com/messersmith
messersmith_power_introductory_algebra_1e_ch4_7_10
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