Algebra I Chapter 8

Mixed Problem SolvingFor mixed problem-solving practice,see page 751.8–3 Factoring Trinomials: x 2 + bx + c (pp. 434–439)Factor each trinomial.32. y 2 + 7y + 12 33. x 2 - 9x - 3634. b 2 + 5b - 6 35. 18 - 9r + r 2Solve each equation. Check the solutions.36. y 2 + 13y + 40 = 037. x 2 - 5x - 66 = 038. SOCCER In order for a town to host aninternational soccer game, its field’slength must be 110–120 yards, and itswidth must be 70–80 yards. GreenMeadows soccer field is 30 yardslonger than it is wide. Write anexpression for the area of therectangular field. If the area of thefield is 8800 square yards, will GreenMeadows be able to host aninternational game? Explain.Example 5 Factor x 2 - 9x + 20.b = -9 and c = 20, so m + n is negative andmn is positive. Therefore, m and n must bothbe negative. List the negative factors of 20, andlook for the pair of factors with a sum of -9.Factors of 20-1, -20-2, -10-4, -5Sum of Factors-21-12-9The correct factors are -4 and -5.x 2 - 9x + 20 = (x + m)(x + n) Write the pattern.= (x - 4)(x - 5) m = -4 andn = -58–4 Factoring Trinomials: ax 2 + bx + c (pp. 441–446)Factor each trinomial, if possible. If thetrinomial cannot be factored usingintegers, write prime.39. 2a 2 - 9a + 3 40. 2m 2 + 13m - 2441. 12b 2 + 17b + 6 42. 3n 2 - 6n - 45Solve each equation. Check the solutions.43. 2r 2 - 3r - 20 = 0 44. 40x 2 + 2x = 2445. BASEBALL Victor hit a baseball into theair that modeled the equationh = -16 t 2 + 36t + 1, where h is theheight in feet and t is the time inseconds. How long was the ball in theair if Casey caught the ball 9 feet abovethe ground on its way down?Example 6 Factor 12x 2 + 22x - 14.12x 2 + 22x - 14 = 2(6 x 2 + 11x - 7)Factor.So, a = 6, b = 11, and c = -7. Since b ispositive, m + n is positive. Since c isnegative, mn is negative. So either m or n isnegative. List the factors of 6(-7) or -42,where one factor in each pair is negative.The correct factors are -3 and 14.6x 2 + 11x - 7 = 6x 2 + mx + nx - 7= 6x 2 - 3x + 14x - 7= (6x 2 - 3x) + (14x - 7)= 3x(2x - 1) + 7(2x - 1)= (2x - 1)(3x + 7)Thus, the complete factorization of12x 2 + 22x - 14 is 2(2x - 1)(3x + 7).**Chapter** 8 Study Guide and Review 463

CHAPTER8Study Guide and Review8–5 Factoring Differences of Squares (pp. 447–452)Factor each polynomial, if possible. Ifthe polynomial cannot be factored,write prime.46. 64 - 4s 2 47. 2y 3 - 128y48. 9b 2 - 20 49. _ 1 4 n 2 -_916 r 2Solve each equation by factoring. Checkthe solutions.50. b 2 - 16 = 0 51. 25 - 9y 2 = 052. 16a 2 = 81 53. _ 2549 - r 2 = 054. EROSION A boulder breaks loose fromthe face of a mountain and falls towardthe water 576 feet below. The distanced that the boulder falls in t seconds isgiven by the equation d = 16t 2 . Howlong does it take the boulder to hit thewater?Example 7 Solve y 2 + 9 = 90 byfactoring.y 2 + 9 = 90 Original equationy 2 - 81 = 0Subtract 90 from each side.y 2 - (9 ) 2 = 0 y 2 = y · y and 81 = 9 · 9(y + 9)(y - 9) = 0 Factor the difference ofsquares.y + 9 = 0 or y - 9 = 0y = 9The roots are -9 and 9.Zero Product Propertyy = -9 Solve each equation.8–6 Perfect Squares and Factoring (pp. 454–460)Factor each polynomial, if possible.If the polynomial cannot be factored,write prime.55. a 2 + 18a + 81 56. 9k 2 - 12k + 457. 4 - 28r + 49r 2 58. 32n 2 - 80n + 50Solve each equation. Check the solutions.59. 6b 3 - 24b 2 + 24b = 0 60. 144b 2 = 3661. 49m 2 - 126m + 81 = 0 62. (c - 9) 2 = 14463. PICTURE FRAMING A picture thatmeasures 7 inches by 7 inches is beingframed. The area of the frame is32 square inches. What is the widthof the frame?Example 8 Solve (x - 4) 2 = 121.(x - 4) 2 = 121 Original equationx - 4 = ± √ 121 Square Root Propertyx - 4 = ±11 121 = 11 · 11x = 4 ± 11Add 4 to each side.x = 4 + 11 or x = 4 - 11 Separate into twoequations.= 15 = -7The roots are -7 and 15.464 **Chapter** 8 Factoring

- Page 2 and 3: GET READY for Chapter 8Diagnose Rea
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