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Chapter 4, continued } 7. x 5 24 } (n 2 8)(n 2 3) 5 0 } n2850 or n2350 n58 or n53 } z 2 3z 2 40 5 0 2 (z 1 5)(z 2 8) 5 0 10. } 12. 12. Ï } } } } } } } } } } } } } a54 } Ï51 } } } 221 2 3Ï5 } } } (50 1 5x) + (140 2 10x) R(x) 5 250(x 2 14)(x 1 10) } } 32 1 4Ï3 5} 61 17. 5x 2 5 80 x 5 16 18. z 2 2 7 5 29 z 2 5 36 2 } } x 5 6Ï16 z 5 6Ï 36 x 5 64 z 5 66 19. 3(x 2 2) 5 40 2 40 (x 2 2)2 5 } 3 14 1 (210) 2 x5}5}52 Î40 } To maximize revenue, each DVD player should cost 140 2 10(2) 5 $120. x2256 } 3 R(2) 5 250(2 2 14)(2 1 10) 5 7200 x2256} } + } } The maximum monthly revenue is $7200. } } Ï40 Ï3 Ï3 Ï3 } Ï120 x2256} 3 Lesson 4.5 } 4.5 Guided Practice (pp. 266–269) } } 1. Ï 27 5 Ï 9 + Ï 3 5 3Ï 3 } } } } } } 3. Ï 10 + Ï 15 5 Ï 150 5 Ï 25 + Ï 6 5 5Ï 6 } } } Ï 4 + Ï 30 x2256} 3 2Ï30 } 2. Ï 98 5 Ï 49 + Ï 2 5 7Ï 2 } } 29 1 Ï 7 R(x) 5 210 + 5(x 2 14)(x 1 10) } } 5} 74 R(x) 5 210(x 2 14)(5x 1 50) } } } } R(x) 5 (210x 1 140)(5x 1 50) } } 32 1 4Ï 3 4 8 1 Ï3 4 16. } } + } } } } 5 } } 5 }} 8 2 Ï3 8 1 Ï3 64 1 8Ï3 2 8Ï 3 2 3 8 2 Ï3 5 } } 29 1 Ï7 21 9 2 Ï7 21 15. } } + } } } } 5 } } 5 }} 9 1 Ï7 9 2 Ï7 81 2 9Ï7 1 9Ï7 2 7 9 1 Ï7 Price Monthly Sales revenue 5 (dollars/DVD + (DVD players) player) (dollars) } } } } 5 } } } 8 2 2Ï11 x 5 2}2 } } 5} 5 2x 1 5 5 0 Copyright © by McDougal Littell, a division of Houghton Mifflin Company. } } 4x 1 20x 1 25 5 0 p1q 2 } 8 2 2Ï 11 2 2 4 2 Ï 11 14. } } + } } } } 5 } } 5 }} 4 1 Ï 11 4 2 Ï11 16 2 4Ï11 1 4Ï 11 2 11 4 1 Ï11 2 R(x) } } } } (2x 1 5)(2x 1 5) 5 0 13. } 242 2 6Ï5 or a 2 4 5 0 or } 5} 5} 44 22 (7a 2 2)(a 2 4) 5 0 2 } Ï19 Ï19 Ï21 Ï399 19 }5} } 5 } } + } } 5 } 21 21 Ï 21 Ï 21 Ï 21 s53 or 7a 2 2 30a 1 8 5 0 a 5 }7 } Ï15 26 242 2 6Ï 5 26 7 1 Ï5 13. } } + } } } } 5 } } 5 }} 7 2 Ï5 7 1 Ï5 49 1 7Ï5 2 7Ï 5 2 5 7 2 Ï5 or s 2 3 5 0 7a 2 2 5 0 Ï15 } (5s 1 1)(s 2 3) 5 0 11. } 15 }5} } 5 } 2 4 Ï4 } } } 5s2 2 14s 2 3 5 0 1 s 5 2}5 } 2Ï51 z58 5s 1 1 5 0 } 6. 5} 5} 12 6 or z 2 8 5 0 z 5 25 or } 3 8 } 8. n 2 2 11n 1 24 5 0 z1550 Ï9 Ï64 } x1450 or x 5 25 or 9. 9 64 }5} } 5 } 5. (x 1 5)(x 1 4) 5 0 x1550 } Ï Ï Ï36 Ï 11 Ï 11 6 36 11 7. 5} 8. } 5 } 5 } 5 Ï49 Ï49 7 Ï}25 5 } Ï25 Ï6 Ï6 Ï5 Ï30 6 9. } 5 } 5 } + } 5 } Ï 5 Ï5 Ï5 Ï5 5 Ï9 Ï9 Ï8 Ï72 Ï36 + Ï2 6Ï 2 3Ï 2 9 10. } 5 } 5 } + } 5 } 5 } 5 } 5 } Ï 8 Ï8 Ï8 Ï8 8 8 8 4 Ï 4 + Ï 51 Ï17 Ï17 Ï12 Ï204 17 11. } 5 } 5 } + } 5 } 5 } Ï12 Ï12 Ï12 Ï12 12 12 x 2 1 9x 1 20 5 0 } } 4. Ï 8 + Ï 28 5 Ï 224 5 Ï 16 + Ï 14 5 4Ï 14 x2256} 3 } 2Ï30 x526} 3 Algebra 2 Worked-Out Solution Key 197 Chapter 4, continued } } 0 5 216t 2 1 30 } 30 16 } Î16 30 6 } 5t } } } } } } } } 61.4 ø t Ï96 5 Ï4 + Ï24 5 2Ï24 5 2Ï4 + Ï6 5 4Ï6 Reject the negative solution, 21.4, because time must be positive. The container will fall for about 1.4 seconds before it hits the ground. or Ï96 5 Ï 16 + Ï6 5 4Ï6 } x569 22. s 2 5 169 2. To “rationalize the denominator” of a quotient containing square roots means to eliminate the radical from the denominator. } } } } } } } } } } } } 8. 5Ï 2 4 + 3Ï 10 5 15Ï 240 5 151 Ï 16 + Ï 15 2 } } Ï } } Ï5 Ï5 5 }5} } 5 } 4 16 Ï16 10. Ï } } } } } } Ï13 } } } } } } } } } } } } Ï2 4Ï2 2 Ï10 Ï2 4 2 Ï5 17. } } + } } } } 5 } } 5 }} 4 1 Ï5 4 2 Ï5 16 2 4Ï5 1 4Ï5 2 5 4 1 Ï5 } Algebra 2 Worked-Out Solution Key x 5 610 31. 4(x 2 1)2 5 8 t2 20 }57 (x 2 1)2 5 2 } x 2 1 5 6Ï2 t 2 5 140 } } } } 5 2 Ï6 1 5 2 Ï6 1 16. } } + } } } } 5 } } 5 }} 5 1 Ï6 5 2 Ï6 25 2 5Ï6 1 5Ï6 2 6 5 1 Ï6 } 5 2 Ï6 5} 19 } x 5 6Ï100 } t 5 6Ï 140 } 5 21 2 Ï 3 } x 2 5 100 } t2 30. } 1 8 5 15 20 2 1 2Ï3 2 1 2Ï 3 2 1 1 Ï3 2 15. } 5} } + } } } } 5 } } 5 }} 22 1 2 Ï3 1 1 Ï3 1 1 Ï3 2 Ï3 2 3 1 2 Ï3 4Ï2 2 Ï 10 x2 25 }54 r 5 6Ï 5 } Ï 4 + Ï 91 } 5} 11 x2 29. } 2 6 5 22 25 r2 5 5 } } } w 5 6Ï71 } 7r 2 5 35 Ï91 2Ï91 5} 5} 28 14 } w 2 5 71 28. 7r 2 2 10 5 25 } Ï364 Ï28 } 27. 23w 2 5 2213 p 5 6Ï 16 + Ï 7 } } } Ï13 z 5 65 } 5}+}5} 5} Ï}28 5} 28 28 Ï28 Ï28 Ï28 13 x 5 62Ï21 } } } z 5 6 Ï25 p 5 64Ï 7 } } } x 5 6 Ï 4 + Ï21 p 5 6Ï 112 Ï18 Ï18 Ï11 Ï198 Ï9 + Ï22 3Ï22 Î}1811 5 } 5}+}5} 5} 5} 11 11 11 Ï 11 Ï 11 Ï 11 } z 2 5 25 } } 7 7Ï12 Ï 12 7 7Ï 3 12. } } + } } 5 } } 5 } 5 } 12 6 Ï 12 Ï 12 Ï 12 } } p 5 112 } Ï35 Ï35 35 }5} } 5 } 6 36 Ï36 8 8Ï 3 Ï3 8 11. } } + } } 5 } } 5 } 3 Ï3 Ï3 Ï3 } 25. 6z 2 5 150 2 } } } } 26. 4p2 5 448 } 5 151 4Ï 15 2 5 60Ï 15 } } } 7. 4Ï 6 + Ï 6 5 4Ï 36 5 4(6) 5 24 } a 5 6 Ï25 + Ï2 } 6. Ï 3 + Ï 27 5 Ï 81 5 9 } s 5 6 13 x 5 6 Ï84 } } a 5 6Ï 50 24. x 2 5 84 5. Ï 150 5 Ï 25 + Ï 6 5 5Ï 6 } } s 5 6 Ï169 a 5 65 Ï2 4. Ï 192 5 Ï 64 + Ï 3 5 8Ï 3 } 23. a 2 5 50 } x 5 1 6 Ï2 } t 5 6Ï 4 + Ï35 } t 5 62Ï 35 Copyright © by McDougal Littell, a division of Houghton Mifflin Company. } } x 5 6 Ï 81 expression. 3. Ï 28 5 Ï 4 + Ï 7 5 2Ï 7 } 5x2 5 405 } } } } x 2 5 81 } } number solutions: x 5 Ï 81 , and x 5 2Ï81 . 1. In the expression Ï 72 , 72 is called the radicand of the } } 21. Because 81 > 0, the equation x 2 5 81 has two real- Skill Practice 198 } 20. The expression was not completely simplified. 4.5 Exercises (pp. 269–271) 14. } 19. C; Ï 108 5 Ï 36 + Ï 3 5 6Ï 3 } 13. } } 5 2}} 6 } 5 t2 } } } 6 1 3Ï 10 1 2Ï7 1 Ï70 230 5 216t 2 9. } } 3 1 Ï 7 2 1 Ï10 6 1 3Ï 10 1 2Ï7 1 Ï 70 3 1 Ï7 18. } } + } } } } 5 } } 5 }} 2 2 Ï 10 2 1 Ï10 4 1 2Ï 10 2 2Ï 10 2 10 2 2 Ï10 h 5 216t 2 1 h0 20. Chapter 4, continued 32. 7(x 2 4)2 2 18 5 10 33. 2(x 1 2)2 2 5 5 8 Problem Solving 7(x 2 4) 5 28 2(x 1 2)2 5 13 (x 2 4)2 5 4 (x 1 2)2 5 } 2 2 h 5 216t2 1 40 13 Ï } } } Ï26 x 1 2 5 6} 2 x 5 4 6 2 5 6, 2 } Ï26 x 5 22 6 } 2 34. C; 3(x 1 2)2 1 4 5 13 40 16 } 5 t2 Ï } 40 6 } 5t 16 61.6 ø t Reject the negative solution, 21.6, because time must be positive. The diver is in the air for about 1.6 seconds. g 39. h 5 2} t 2 1 h0 2 32 2 Earth: 0 5 2} t 1 150 2 3(x 1 2) 5 9 2 } x 1 2 5 6Ï3 240 5 216t 2 } Ï13 Ï2 x 1 2 5 6} } 2 } } Ï2 Ï2 x 2 4 5 62 0 5 216t2 1 40 } 13 x1256 } 2 x 2 4 5 6Ï4 (x 1 2)2 5 3 h 5 216t2 1 h0 38. 0 5 216t 2 1 150 } x 5 22 6 Ï3 2150 5 216t 2 35. One method for solving the equation is to use the special 150 16 } 5 t2 factoring pattern known as the difference of two squares. Ï x2 2 4 5 0 (x 1 2)(x 2 2) 5 0 x1250 } 150 6 } 5t 16 or x 5 22 or x2250 x52 Another method for solving the equation is to use square roots. 63.1 ø t It takes the rock about 3.1 seconds to hit the surface of Earth. 12 t 2 1 150 Mars: 0 5 2} 2 0 5 26t 2 1 150 x2 2 4 5 0 Copyright © by McDougal Littell, a division of Houghton Mifflin Company. x2 5 4 2150 5 26t2 } x 5 6 Ï4 25 5 t 2 x 5 62 } 6Ï 25 5 t 2 65 5 t 36. Sample answer: a. x 5 121 2 It takes the rock 5 seconds to hit the surface of Mars. b. x 2 5 0 76 t 2 1 150 Jupiter: 0 5 2} 2 c. x 5 236 2 0 5 238t 2 1 150 37. a(x 1 b)2 5 c 2150 5 238t 2 c (x 1 b)2 5 }a 150 38 } 5 t2 Îc } x 1 b 5 6 }a Ï } 150 Ïc } Ïa 6 } 5t 38 Ïa Ïa 62 ø t } x 1 b 5 6} } + } } } Ï ca x 1 b 5 6} a } Ï ca x 5 2b 6 } a It takes the rock about 2 seconds to hit the surface of Jupiter. 30 t2 1 150 Saturn: 0 5 2} 2 0 5 215t 2 1 150 2150 5 215t 2 10 5 t 2 } 6Ï 10 5 t 63.2 ø t It takes the rock about 3.2 seconds to hit the surface of Saturn. Algebra 2 Worked-Out Solution Key 199 Chapter 4, continued 2 Pluto: 0 5 2}2 t 2 1 150 0 5 2t 2 1 150 05 150 5 t 2 } 2 2 } 2 Ï3 }t 2 1 Ïh0 2 2:d *w } } 6Ï150 5 t } 2:d 2Ï3 *w 0 5 Ï h0 2 } t 612.2 ø t } It takes the rock about 12.2 seconds to hit the surface of Pluto. h 5 0.019s2 5 5 0.019s2 20 5 0.019s2 } 5 s2 5 0.019 } 5 s2 } } 5 20 0.019 Ï 20 6 } 5s 0.019 6 } 5s 0.019 616.2 ø s 632.4 ø s 16.2 knots 32.4 knots The wind speed required to generate 20 foot waves is twice the wind speed required to generate 5 foot waves. 41. a. Area of circle 5 Area of square :r 2 5 10 2 :r 2 5 100 } 2:d 2Ï3 } t 5 Ï h0 *w } *wÏh0 } } *wÏ3h0 Ï3 t5} } + } } 5 } 2 6:d 2 2:d Ï3 Ï3 Mixed Review for TAKS 44. B; The line is dashed, so choices C and D can be eliminated. The half-plane above the line is shaded, so choice A can be eliminated. The inequality y > 2x 2 3 is graphed. 45. H; 3x 1 y 5 21 l y 5 23x 2 1 l m 5 23 1 1 2x 1 3y 5 6 l y 5 }3 x 1 2 l m 5 }3 The lines are perpendicular because 231 }3 2 5 21. 1 Problem Solving Workshop 4.5 (p. 273) b. :r 5 100 2 1. 2x 2 2 12x 1 10 5 0 100 r2 5 } : x51 } Ï 100 r56 } : r ø 65.6 The radius of the circular lot should be about 5.6 feet. c. :r 2 5 s2 X 0 1 2 3 4 5 6 X=1 or x55 Y1 10 0 -6 -8 -6 0 10 s2 r2 5 } :F 2. x 2 1 7x 1 12 5 0 Î } s2 r56 } : x 5 24 R 5 0.00829s2 42. a. 5 5 0.00829s Î 2 5 } 5 s2 0.00829 } 5 X -6 -5 -4 -3 -2 -1 0 X=-4 or x 5 23 Y1 6 2 0 0 2 6 12 6 } 5s 0.00829 624.6 ø s Reject the negative solution, 224.6, because speed must be positive. The speed of the racing cyclist is about 24.6 miles per hour. b. R 5 0.00829s2 R 5 0.00829(2s)2 R 5 0.00829(4s2) R 5 4(0.00829s2) The air resistance quadruples when the cyclist’s speed doubles. 200 Algebra 2 Worked-Out Solution Key 3. 9x 2 2 30x 1 25 5 0 x ø 1.7 X 1.4 1.5 1.6 1.7 1.8 1.9 2.0 X=1.7 Y1 .64 .25 .04 .01 .16 .49 1 o r e Z X=1.6666666 Y=0 Copyright © by McDougal Littell, a division of Houghton Mifflin Company. Ï } The pool is completely drained when h 5 0. 2150 5 2t 2 40. 2 } Ï3 } t2 1 Ïh0 2 2:d *w h5 43. Chapter 4, continued 4. 7x 2 2 3 5 0 X -1 -.9 -.8 -.7 -.6 -.5 -.4 X=-.7 Y1 4 2.67 1.48 .43 -.48 -1.25 -1.88 8. h 5 216t 2 1 h0 X .2 .3 .4 .5 .6 .7 .8 X=.6 0 5 216t2 1 30 Y1 -2.72 -2.37 -1.88 -1.25 -.48 .43 1.48 X Y1 1 14 1.1 10.6 4 1.2 .9 66 1.3 2.9 6 1.4 1.36 1.5 6 1.6 10.9 - 6 X=1.4 Zero X=1.36 306 94 The shellfish hits the ground between 1.3 and 1.4 seconds after it is dropped. Y= 0 The shellfish hits the ground about 1.4 seconds after it is dropped. 9. h 5 216t 2 1 h0 The tables show that x is between 20.7 and 20.6 or x is between 0.6 and 0.7. 5. x 1 3x 2 6 5 0 4 5 216t2 1 29 0 5 216t2 1 25 2 X -4.8 -4.7 -4.6 -4.5 -4.4 -4.3 -4.2 X=-4.4 Y1 2.64 1.99 1.36 .75 .16 -.41 -.96 X 1 1.1 1.2 1.3 1.4 1.5 1.6 X=1.4 X Y1 1 9 1.1 5.6 4 1.2 1.9 6 1.3 2.04 1.4 .36 6 1.5 11 1.6 15.9 - 6 X=1.3 Y1 -2 -1.49 -.96 -.41 .16 .7 5 1.36 Zero X=1.25 The ball is in the air between 1.2 and 1.3 seconds before your friend catches it. Y=0 The ball is in the air 1.25 seconds before your friend catches it. 10. h 5 16t 2 1 h0 Copyright © by McDougal Littell, a division of Houghton Mifflin Company. 0 5 216t2 1 50 The tables show that x is between 24.4 and 24.3 or x is between 1.3 and 1.4. 6. h 5 216t 2 1 h0 The container hits the ground between 1.76 and 1.77 seconds after it is dropped. 0 5 216t 1 100 2 X 2 2.1 2.2 2.3 2.4 2.5 2.6 X=2.5 Y1 36 29.44 22.56 15.36 .84 7 0 -8.16 o r e Z X=2.5 X 1.73 1.74 1.75 1.76 1.77 1.78 1.79 X=1.77 Y=0 The container hits the ground 2.5 seconds after it is dropped. 7. P 5 0.00256s 2 A pressure of 30 lb/ft2 is produced by a wind speed between 108.2 and 108.3 miles per hour. Mixed Review for TEKS (p. 274) 1. B; 416 5 (24 1 2x)(20 1 2x) 2 (24)(20) 0 5 0.00256s 2 2 30 Y1 -.1402 -.0848 -.0295 .02596 .08143 .13696 .19254 Y1 2.1136 1.5584 1 .4384 -.1264 -.6944 -1.266 Area of border 5 Area of frame 2 Area of mirror 30 5 0.00256s 2 X 108 108.1 108.2 108.3 108.4 108.5 108.6 X=108.3 The table feature of the graphing calculator must be set so that the x-values start at 1 and increase in increments of 0.01. Scroll through the table to find the time x at which the height y of the container is 0 feet. 416 5 480 1 88x 1 4x 2 2 480 0 5 4x 2 1 88x 2 416 0 5 4(x 126)(x 2 4) x 1 26 5 0 Zero X=108.25318 Y=0 A pressure of 30 lb/ft2 is produced by a wind speed of about 108.3 miles per hour. or x2450 x 5 226 or x54 Reject the negative value, 226. The greatest possible width of the border is 4 inches. Algebra 2 Worked-Out Solution Key 201 Chapter 4, continued 2. H; h 5 216t 2 1 h0 7. 0 5 216t 1 20 2 672 5 336 1 42x 1 8x 1 x 2 20 0 5 x 2 1 50x 2 336 Î } 0 5 (x 2 6)(x 1 56) 20 t56 } 16 t 5 61.12 Time must be positive, so the pinecone takes about 1.12 seconds to hit the ground. 3. C; y 5 20.0035x(x 2 143.9) y 5 20.0035(x 2 0)(x 2 143.9) The x-intercepts are 0 and 143.9, so the cannon shoots 143.9 feet. 4. G; x2650 or x56 or x 1 56 5 0 Lesson 4.6 4.6 Guided Practice (pp. 275–279) 1. x 2 5 213 2. x 2 5 238 } } x 5 6Ï213 x 5 6Ï238 x 5 6i Ï13 x 5 6i Ï38 } } 3. x 2 1 11 5 3 4 3 }5} x 2 5 28 4 w 5 }3h 2 1 2 4 3 h 1 }h x 2 5 228 } } x 5 6Ï28 x 5 6Ï228 x 5 6i Ï 8 x 5 6i Ï 28 x 5 62i Ï 2 x 5 62i Ï 7 } } 5 225 } 5. 3x 2 2 7 5 231 16 h2 1 } h 2 5 225 9 6. 5x 2 1 33 5 3 3x 5 224 5x 2 5 230 x 2 5 28 x 2 5 26 2 25 9 } h 2 5 225 h 5 81 4. x 2 2 8 5 236 } h 2 1 w 2 5 152 2 } h 5 6Ï81 } x 5 6Ï28 x 5 6Ï26 x 5 6i Ï 8 x 5 6i Ï6 } } } } x 5 62i Ï2 h 5 69 Height must be positive, so the height of the screen is 9 inches. 7. (9 2 i) 1 (26 1 7i) 5 [9 1 (26)] 1 (21 1 7)i 5 3 1 6i 8. (3 1 7i) 2 (8 2 2i) 5 (3 2 8) 1 [7 2 (22)]i 5. A; y 5 23x 2 18x 2 25 2 b 18 x 5 2} 5 } 5 23 2a 2(23) 5 25 1 9i 9. 24 2 (1 1 i) 2 (5 1 9i) 5 [(24 2 1)(i)] 2 (5 1 9i) y 5 23(3) 2 18(23) 2 25 5 2 5 (25 2 i) 2 (5 1 9i) The function y 5 23x 2 2 18x 2 25 has a vertex of (23, 2). 5 210 2 10i 2 6. Let x 5 $.25 price increase. Let R(x) 5 daily revenue. Daily revenue (dollars) 5 Price (dollars/slice) + Number sold (slices) 5 (25 2 5) 1 (21 2 9)i 10. 5 1 3i 1 (27i) 5 5 2 4i The impedance of the circuit is 5 2 4i ohms. 11. i(9 2 i) 5 9i 2 i 2 5 9i 2 (21) R(x) 5 (2 1 0.25x) + (80 2 5x) 5 9i 1 1 R(x) 5 160 2 10x 1 20x 2 1.25x 2 5 1 1 9i R(x) 5 21.25x 1 10x 1 160 2 10 b x 5 2} 5 2} 54 2a 2(21.25) When x 5 4, R is maximized. The pizza shop should charge $2 1 4($.25), or $3 a slice to maximize profit. 202 x 5 256 Reject the negative value, 256. The value of x is 6 feet. Algebra 2 Worked-Out Solution Key 12. (3 1 i)(5 2 i) 5 15 2 3i 1 5i 2 i 2 5 15 1 2i 2 (21) 5 15 1 2i 1 1 5 16 1 2i Copyright © by McDougal Littell, a division of Houghton Mifflin Company. t2 5 } 16 2 New width (ft) + 2(42)(8) 5 (42 1 x)(8 1 x) 16t 2 5 20 w h New area New length 5 (sq ft) (ft)