1. **Problem 1(a)(i):** Find $s$ when $t=26.5$, $u=104.3$, and $a=-2.2$ using the formula $s = ut + \frac{1}{2}at^2$.
2. Substitute values:
$$s = 104.3 \times 26.5 + \frac{1}{2} \times (-2.2) \times (26.5)^2$$
3. Calculate each term:
$$104.3 \times 26.5 = 2764.95$$
$$\frac{1}{2} \times (-2.2) = -1.1$$
$$-1.1 \times (26.5)^2 = -1.1 \times 702.25 = -772.475$$
4. Sum the terms:
$$s = 2764.95 - 772.475 = 1992.475$$
5. Express in standard form to 4 significant figures:
$$s = 1.991 \times 10^3$$
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6. **Problem 1(a)(ii):** Rearrange $s = ut + \frac{1}{2}at^2$ to express $a$ in terms of $u$, $t$, and $s$.
7. Subtract $ut$ from both sides:
$$s - ut = \frac{1}{2}at^2$$
8. Multiply both sides by 2:
$$2(s - ut) = at^2$$
9. Divide both sides by $t^2$:
$$a = \frac{2(s - ut)}{t^2}$$
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10. **Problem 1(b)(i):** Show that the difference between areas of two rectangles is $62$ cm$^2$ leads to $x^2 + 2x - 63 = 0$.
11. Area of first rectangle:
$$(2x + 3)(x - 1) = 2x^2 + 3x - 2x - 3 = 2x^2 + x - 3$$
12. Area of second rectangle:
$$(x + 1)(x - 2) = x^2 - 2x + x - 2 = x^2 - x - 2$$
13. Difference of areas:
$$2x^2 + x - 3 - (x^2 - x - 2) = 2x^2 + x - 3 - x^2 + x + 2 = x^2 + 2x - 1$$
14. Set equal to 62:
$$x^2 + 2x - 1 = 62$$
15. Rearrange:
$$x^2 + 2x - 63 = 0$$
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16. **Problem 1(b)(ii):** Factorize $x^2 + 2x - 63$.
17. Find factors of $-63$ that sum to $2$: $9$ and $-7$.
18. Factorization:
$$(x + 9)(x - 7)$$
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19. **Problem 1(b)(iii):** Solve $x^2 + 2x - 63 = 0$.
20. Set each factor to zero:
$$x + 9 = 0 \Rightarrow x = -9$$
$$x - 7 = 0 \Rightarrow x = 7$$
21. Calculate perimeters:
First rectangle perimeter:
$$2[(2x + 3) + (x - 1)] = 2(3x + 2) = 6x + 4$$
Second rectangle perimeter:
$$2[(x + 1) + (x - 2)] = 2(2x - 1) = 4x - 2$$
22. Difference between perimeters:
$$|6x + 4 - (4x - 2)| = |2x + 6|$$
23. Substitute $x=7$ (positive root):
$$2(7) + 6 = 14 + 6 = 20$$
24. Final answer:
$$20 \text{ cm}$$
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25. **Problem 3(a)(i):** Make $p$ the subject of $5p + 7 = m$.
26. Subtract 7:
$$5p = m - 7$$
27. Divide by 5:
$$p = \frac{m - 7}{5}$$
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28. **Problem 3(a)(ii):** Make $p$ the subject of $y^2 - 2p^2 = h$.
29. Rearrange:
$$-2p^2 = h - y^2$$
30. Divide by $-2$:
$$p^2 = \frac{y^2 - h}{2}$$
31. Take square root:
$$p = \pm \sqrt{\frac{y^2 - h}{2}}$$
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32. **Problem 4(a):** Simplify
$$\frac{x + 3}{x - 2} - \frac{x - 2}{x + 2}$$
33. Find common denominator:
$$(x - 2)(x + 2) = x^2 - 4$$
34. Rewrite:
$$\frac{(x + 3)(x + 2)}{x^2 - 4} - \frac{(x - 2)^2}{x^2 - 4}$$
35. Expand numerators:
$$(x + 3)(x + 2) = x^2 + 5x + 6$$
$$(x - 2)^2 = x^2 - 4x + 4$$
36. Subtract:
$$\frac{x^2 + 5x + 6 - (x^2 - 4x + 4)}{x^2 - 4} = \frac{9x + 2}{x^2 - 4}$$
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37. **Problem 4(b):** Solve
$$2^{12} \div 2^{k/2} = 32$$
38. Rewrite 32 as power of 2:
$$32 = 2^5$$
39. Use division rule:
$$2^{12 - k/2} = 2^5$$
40. Equate exponents:
$$12 - \frac{k}{2} = 5$$
41. Solve for $k$:
$$12 - 5 = \frac{k}{2} \Rightarrow 7 = \frac{k}{2} \Rightarrow k = 14$$
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42. **Problem 5(a):** Find $s$ when $u=5.2$, $t=7$, $a=1.6$.
43. Use formula:
$$s = ut + \frac{1}{2}at^2 = 5.2 \times 7 + \frac{1}{2} \times 1.6 \times 7^2$$
44. Calculate:
$$5.2 \times 7 = 36.4$$
$$\frac{1}{2} \times 1.6 = 0.8$$
$$0.8 \times 49 = 39.2$$
45. Sum:
$$s = 36.4 + 39.2 = 75.6$$
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46. **Problem 5(b)(i):** Simplify
$$3a - 5b - a + 2b = 2a - 3b$$
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47. **Problem 5(b)(ii):** Simplify
$$\frac{5}{3x} \times \frac{9x}{20} = \frac{5 \times 9x}{3x \times 20} = \frac{45x}{60x} = \frac{3}{4}$$
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48. **Problem 5(c)(i):** Solve
$$\frac{15}{x} = -3$$
49. Multiply both sides by $x$:
$$15 = -3x$$
50. Divide by $-3$:
$$x = -5$$
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51. **Problem 5(c)(ii):** Solve
$$4(5 - 3x) = 23$$
52. Expand:
$$20 - 12x = 23$$
53. Subtract 20:
$$-12x = 3$$
54. Divide by $-12$:
$$x = -\frac{1}{4} = -0.25$$
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55. **Problem 5(d):** Simplify
$$(27x^9)^{2/3}$$
56. Rewrite:
$$27^{2/3} \times (x^9)^{2/3}$$
57. Calculate powers:
$$27^{2/3} = (3^3)^{2/3} = 3^{2} = 9$$
$$x^{9 \times \frac{2}{3}} = x^{6}$$
58. Final answer:
$$9x^6$$
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59. **Problem 5(e):** Expand and simplify
$$(3x - 5y)(2x + y) = 6x^2 + 3xy - 10xy - 5y^2 = 6x^2 - 7xy - 5y^2$$
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60. **Problem 6(a)(i):** Factorise
$$5am + 10ap - bm - 2bp = (5a - b)(m + 2p)$$
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61. **Problem 6(a)(ii):** Factorise
$$15(k + g)^2 - 20(k + g) = 5(k + g)(3(k + g) - 4) = 5(k + g)(3k + 3g - 4)$$
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62. **Problem 6(a)(iii):** Factorise
$$4x^2 y^4 = (2xy^2)^2$$
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63. **Problem 6(b):** Expand and simplify
$$(x - 3)(x + 1)(3x - 4)$$
64. First expand first two:
$$(x - 3)(x + 1) = x^2 - 2x - 3$$
65. Multiply by third:
$$(x^2 - 2x - 3)(3x - 4) = 3x^3 - 4x^2 - 6x^2 + 8x - 9x + 12 = 3x^3 - 10x^2 - x + 12$$
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66. **Problem 6(c):** Given
$$(x + a)^2 = x^2 + 22x + b$$
67. Expand left:
$$x^2 + 2ax + a^2 = x^2 + 22x + b$$
68. Equate coefficients:
$$2a = 22 \Rightarrow a = 11$$
$$a^2 = b \Rightarrow b = 11^2 = 121$$
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69. **Problem 7(a):** Simplify
$$\frac{x^2 - 25}{x^2 - x - 20}$$
70. Factor numerator:
$$(x - 5)(x + 5)$$
71. Factor denominator:
$$(x - 5)(x + 4)$$
72. Cancel common factor:
$$\frac{x + 5}{x + 4}$$
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73. **Problem 7(b):** Write as single fraction
$$\frac{x + 5}{x} + \frac{x + 8}{x - 1}$$
74. Common denominator:
$$x(x - 1)$$
75. Rewrite:
$$\frac{(x + 5)(x - 1)}{x(x - 1)} + \frac{(x + 8)x}{x(x - 1)} = \frac{(x + 5)(x - 1) + x(x + 8)}{x(x - 1)}$$
76. Expand numerator:
$$(x + 5)(x - 1) = x^2 - x + 5x - 5 = x^2 + 4x - 5$$
$$x(x + 8) = x^2 + 8x$$
77. Sum numerator:
$$x^2 + 4x - 5 + x^2 + 8x = 2x^2 + 12x - 5$$
78. Final fraction:
$$\frac{2x^2 + 12x - 5}{x(x - 1)}$$
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79. **Problem 8(a)(i):** Simplify
$$7^5 \times 7^6 = 7^{5+6} = 7^{11}$$
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80. **Problem 8(a)(ii):** Simplify
$$7^{15} \div 7^5 = 7^{15-5} = 7^{10}$$
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81. **Problem 8(a)(iii):** Simplify
$$42 + 7 = 49 = 7^2$$
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82. **Problem 8(b):** Simplify
$$(5x^2 \times 2xy^4)^3 = (10x^3 y^4)^3 = 10^3 x^{9} y^{12} = 1000 x^9 y^{12}$$
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83. **Problem 8(c)(i):** Find HCF of
$$P = 2^5 \times 3^3 \times 7$$
$$Q = 540 = 2^2 \times 3^3 \times 5$$
84. HCF is product of lowest powers:
$$2^2 \times 3^3 = 4 \times 27 = 108$$
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85. **Problem 8(c)(ii):** Find LCM:
86. LCM is product of highest powers:
$$2^5 \times 3^3 \times 5 \times 7 = 32 \times 27 \times 5 \times 7 = 30240$$
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87. **Problem 8(c)(iii):** Find smallest $R$ so that $P \times R$ is a cube.
88. Prime factorization of $P$:
$$2^5 \times 3^3 \times 7^1$$
89. For cube, powers must be multiples of 3.
90. Adjust powers:
- $2^5$: needs $2^{1}$ to make $2^{6}$
- $3^3$: already cube
- $7^1$: needs $7^{2}$ to make $7^{3}$
91. So
$$R = 2^1 \times 7^2 = 2 \times 49 = 98$$
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92. **Problem 8(d)(i):** Factorise
$$x^2 - 3x - 28 = (x - 7)(x + 4)$$
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93. **Problem 8(d)(ii):** Factorise
$$7(a + 2b)^2 + 4a(a + 2b) = (a + 2b)(7(a + 2b) + 4a) = (a + 2b)(11a + 14b)$$
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94. **Problem 8(e):** Solve
$$3^{2x - 1} = \frac{1}{9^x} \times 3^{2y - x}$$
95. Rewrite $\frac{1}{9^x} = 9^{-x} = (3^2)^{-x} = 3^{-2x}$
96. Equation becomes:
$$3^{2x - 1} = 3^{-2x} \times 3^{2y - x} = 3^{-2x + 2y - x} = 3^{2y - 3x}$$
97. Equate exponents:
$$2x - 1 = 2y - 3x$$
98. Rearrange:
$$2y = 2x - 1 + 3x = 5x - 1$$
99. Solve for $y$:
$$y = \frac{5x - 1}{2}$$
Algebra Assignment 14
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