math Olympiad

hard calculation question

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1. If 3x + 5 = 20, what is the value of x?

Solution
Correct: A
Subtract 5 from both sides: 3x = 15. Divide by 3: x = 5.

2. Simplify (2x - 3)(x + 4).

Solution
Correct: A
Use FOIL: 2x·x + 2x·4 - 3·x - 3·4 = 2x² + 8x - 3x - 12 = 2x² + 5x - 12.

3. Solve x² - 9x + 18 = 0.

Solution
Correct: A
Factor: (x - 3)(x - 6) = 0 ⇒ x = 3 or 6.

4. If f(x) = 4x - 7, find f(5).

Solution
Correct: A
Substitute: f(5) = 4·5 - 7 = 20 - 7 = 13.

5. What is the slope of the line 3x - 2y = 12?

Solution
Correct: A
Rearrange to y = mx + b: 2y = 3x - 12 ⇒ y = (3/2)x - 6 ⇒ slope = 3/2.

6. Evaluate 5a² - 2a when a = 3.

Solution
Correct: A
Substitute: 5·3² - 2·3 = 5·9 - 6 = 45 - 6 = 39.

7. Factor completely x² - 16.

Solution
Correct: A
Difference of squares: x² - 16 = (x - 4)(x + 4).

8. Solve 2(x - 3) + 4 = 3x - 5.

Solution
Correct: A
Expand: 2x - 6 + 4 = 3x - 5 ⇒ 2x - 2 = 3x - 5 ⇒ -2 + 5 = x ⇒ x = 3.

9. If y = 2x + 1 and x = 4, what is y?

Solution
Correct: A
Substitute: y = 2·4 + 1 = 8 + 1 = 9.

10. Simplify (x²)³.

Solution
Correct: B
Power of a power: (x²)³ = x^(2·3) = x⁶.

11. Find the x-intercept of 2x + 3y = 12.

Solution
Correct: A
Set y = 0: 2x = 12 ⇒ x = 6.

12. Expand (x + 5)².

Solution
Correct: B
Perfect square: (x + 5)² = x² + 2·5x + 25 = x² + 10x + 25.

13. If 4x - 7 = 2x + 11, what is x?

Solution
Correct: A
Subtract 2x: 2x - 7 = 11. Add 7: 2x = 18 ⇒ x = 9.

14. Simplify (3x²y)(2xy³).

Solution
Correct: A
Multiply coefficients and add exponents: 3·2 x^(2+1) y^(1+3) = 6x³y⁴.

15. Solve x/3 + 2 = 5.

Solution
Correct: A
Subtract 2: x/3 = 3. Multiply by 3: x = 9.

16. What is the y-intercept of y = -3x + 7?

Solution
Correct: A
Slope-intercept form gives y-intercept as 7.

17. Factor x² + 7x + 12.

Solution
Correct: A
Find factors of 12 that add to 7: 3 and 4 ⇒ (x + 3)(x + 4).

18. If 2x² = 50, what is the positive value of x?

Solution
Correct: A
Divide by 2: x² = 25 ⇒ x = 5 (positive root).

19. Simplify (x² - 4x)/(x - 4).

Solution
Correct: A
Factor numerator: x(x - 4)/(x - 4) = x (for x ≠ 4).

20. Solve 5 - 2x = 3x + 15.

Solution
Correct: A
Add 2x: 5 = 5x + 15. Subtract 15: -10 = 5x ⇒ x = -2.

21. Evaluate 2a + 3b when a = 4 and b = -2.

Solution
Correct: A
Substitute: 2·4 + 3·(-2) = 8 - 6 = 2.

22. What is the degree of the polynomial 3x³ + 2x² - 5x + 1?

Solution
Correct: A
The highest exponent is 3, so degree = 3.

23. If 3(x - 2) = 2(x + 1), what is x?

Solution
Correct: A
Expand: 3x - 6 = 2x + 2. Subtract 2x: x - 6 = 2 ⇒ x = 8.

24. Simplify (x + 3)(x - 3).

Solution
Correct: A
Difference of squares: (x + 3)(x - 3) = x² - 9.

25. Find the vertex of the parabola y = x² - 4x + 5.

Solution
Correct: A
x = -b/(2a) = 4/2 = 2. y = 2² - 4·2 + 5 = 4 - 8 + 5 = 1 ⇒ vertex (2, 1).

26. Solve 7x - 14 = 0.

Solution
Correct: A
Add 14: 7x = 14 ⇒ x = 2.

27. If g(x) = x² - 2x, find g(3).

Solution
Correct: A
Substitute: g(3) = 3² - 2·3 = 9 - 6 = 3.

28. Simplify (2x²)³.

Solution
Correct: C
Power of product: 2³(x²)³ = 8x⁶.

29. What is the sum of roots of x² - 5x + 6 = 0?

Solution
Correct: A
For ax² + bx + c = 0, sum of roots = -b/a = 5/1 = 5.

30. Solve 4x + 7 = 3x - 2.

Solution
Correct: A
Subtract 3x: x + 7 = -2. Subtract 7: x = -9.

31. Evaluate (x + 2)² when x = 3.

Solution
Correct: A
Substitute: (3 + 2)² = 5² = 25.

32. Factor 2x² - 8.

Solution
Correct: A
Factor out 2: 2(x² - 4) = 2(x - 2)(x + 2).

33. If 1/x = 2/5, what is x?

Solution
Correct: A
Cross-multiply: 5 = 2x ⇒ x = 5/2.

34. Simplify (x² + 3x + 2)/(x + 1).

Solution
Correct: A
Factor numerator: (x + 1)(x + 2)/(x + 1) = x + 2 (x ≠ -1).

35. Find the constant term in the expansion of (x + 4)².

Solution
Correct: A
(x + 4)² = x² + 8x + 16 ⇒ constant term = 16.

36. Solve x² = 49.

Solution
Correct: A
Take square root: x = ±√49 = ±7.

37. If 2x - 3y = 12 and y = 2, find x.

Solution
Correct: A
Substitute y = 2: 2x - 6 = 12 ⇒ 2x = 18 ⇒ x = 9.

38. Simplify (x³)(x⁴).

Solution
Correct: A
Product rule: x³·x⁴ = x^(3+4) = x⁷.

39. What is the axis of symmetry of y = x² - 6x + 8?

Solution
Correct: A
x = -b/(2a) = 6/2 = 3.

40. Evaluate 3x² - 2x + 1 for x = 2.

Solution
Correct: A
Substitute: 3·4 - 2·2 + 1 = 12 - 4 + 1 = 9.

41. Factor x² - x - 6.

Solution
Correct: A
Find factors of -6 that add to -1: -3 and 2 ⇒ (x - 3)(x + 2).

42. Solve 3x + 4 = 2x + 10.

Solution
Correct: A
Subtract 2x: x + 4 = 10 ⇒ x = 6.

43. If h(x) = -x² + 4x, find the maximum value.

Solution
Correct: A
Vertex at x = -b/(2a) = -4/(-2) = 2. h(2) = -4 + 8 = 4.

44. Simplify (x² - 9)/(x - 3).

Solution
Correct: A
Factor numerator: (x - 3)(x + 3)/(x - 3) = x + 3 (x ≠ 3).

45. Find the y-value when x = 1 on the line 2x + 3y = 11.

Solution
Correct: A
Substitute x = 1: 2 + 3y = 11 ⇒ 3y = 9 ⇒ y = 3.

46. Expand (2x - 1)².

Solution
Correct: A
Perfect square: (2x)² - 2·2x·1 + 1² = 4x² - 4x + 1.

47. Solve 5x - 3 = 2x + 12.

Solution
Correct: A
Subtract 2x: 3x - 3 = 12. Add 3: 3x = 15 ⇒ x = 5.

48. Evaluate (x - 4)² when x = 1.

Solution
Correct: A
Substitute: (1 - 4)² = (-3)² = 9.

49. Factor 3x² + 6x.

Solution
Correct: A
Factor out 3x: 3x(x + 2).

50. If 2x = 8, what is x²?

Solution
Correct: A
Divide by 2: x = 4 ⇒ x² = 16.

51. Simplify (x⁵)/(x²).

Solution
Correct: A
Quotient rule: x^(5-2) = x³.

52. Find the product of roots of x² - 8x + 15 = 0.

Solution
Correct: A
For ax² + bx + c = 0, product of roots = c/a = 15/1 = 15.

53. Solve 9 - x = 2x + 3.

Solution
Correct: A
Add x: 9 = 3x + 3. Subtract 3: 6 = 3x ⇒ x = 2.

54. If f(x) = x² + 1, find f(-3).

Solution
Correct: A
Substitute: f(-3) = (-3)² + 1 = 9 + 1 = 10.

55. Simplify (x + 1)² - (x - 1)².

Solution
Correct: A
Expand: (x² + 2x + 1) - (x² - 2x + 1) = 4x.

56. Find the x-coordinate of the vertex of y = 2x² - 8x + 5.

Solution
Correct: A
x = -b/(2a) = 8/4 = 2.

57. Evaluate 2x + 3y when x = 5 and y = -1.

Solution
Correct: A
Substitute: 2·5 + 3·(-1) = 10 - 3 = 7.

58. Factor x² + 2x - 15.

Solution
Correct: A
Find factors of -15 that add to 2: 5 and -3 ⇒ (x + 5)(x - 3).

59. Solve x/2 - 3 = 1.

Solution
Correct: A
Add 3: x/2 = 4. Multiply by 2: x = 8.

60. If 3x - 2y = 7 and x = 3, find y.

Solution
Correct: A
Substitute x = 3: 9 - 2y = 7 ⇒ -2y = -2 ⇒ y = 1.

61. Simplify (2x)³.

Solution
Correct: A
Power of product: 2³x³ = 8x³.

62. What is the discriminant of x² - 4x + 4 = 0?

Solution
Correct: A
Discriminant = b² - 4ac = (-4)² - 4·1·4 = 16 - 16 = 0.

63. Solve 4x + 5 = 2x + 13.

Solution
Correct: A
Subtract 2x: 2x + 5 = 13. Subtract 5: 2x = 8 ⇒ x = 4.

64. Evaluate x² - 5x + 6 for x = 4.

Solution
Correct: A
Substitute: 16 - 20 + 6 = 2.

65. Factor 5x² - 5.

Solution
Correct: A
Factor out 5: 5(x² - 1) = 5(x - 1)(x + 1).

66. If 1/(x + 2) = 1/5, what is x?

Solution
Correct: A
Cross-multiply: x + 2 = 5 ⇒ x = 3.

67. Simplify (x² - 4x + 4)/(x - 2).

Solution
Correct: A
Factor numerator: (x - 2)²/(x - 2) = x - 2 (x ≠ 2).

68. Find the slope of the line through (2, 3) and (4, 7).

Solution
Correct: A
Slope = (7 - 3)/(4 - 2) = 4/2 = 2.

69. Expand (x - 5)(x + 2).

Solution
Correct: A
FOIL: x² + 2x - 5x - 10 = x² - 3x - 10.

70. Solve 6x - 7 = 3x + 8.

Solution
Correct: A
Subtract 3x: 3x - 7 = 8. Add 7: 3x = 15 ⇒ x = 5.

71. If p(x) = x³ - x, find p(2).

Solution
Correct: A
Substitute: 8 - 2 = 6.

72. Simplify (x⁻²)(x⁵).

Solution
Correct: A
Product rule: x^(-2+5) = x³.

73. Find the x-intercept of y = 3x - 9.

Solution
Correct: A
Set y = 0: 3x = 9 ⇒ x = 3.

74. Evaluate (x + 1)/(x - 1) when x = 3.

Solution
Correct: A
Substitute: (3 + 1)/(3 - 1) = 4/2 = 2.

75. Factor x² - 10x + 25.

Solution
Correct: A
Perfect square: x² - 10x + 25 = (x - 5)².

76. Solve 2x² - 8 = 0.

Solution
Correct: A
Add 8: 2x² = 8 ⇒ x² = 4 ⇒ x = ±2.

77. If 4x - 3y = 5 and y = 1, find x.

Solution
Correct: A
Substitute y = 1: 4x - 3 = 5 ⇒ 4x = 8 ⇒ x = 2.

78. Simplify (x²y³)².

Solution
Correct: A
Power of product: x^(2·2) y^(3·2) = x⁴y⁶.

79. What is the minimum value of y = x² - 2x + 4?

Solution
Correct: A
Vertex at x = 1: y = 1 - 2 + 4 = 3.

80. Solve 3(x + 2) = 2(x + 5).

Solution
Correct: A
Expand: 3x + 6 = 2x + 10. Subtract 2x: x + 6 = 10 ⇒ x = 4.

81. Evaluate 2x² - x when x = -1.

Solution
Correct: A
Substitute: 2(-1)² - (-1) = 2 + 1 = 3.

82. Factor 4x² - 1.

Solution
Correct: A
Difference of squares: (2x)² - 1² = (2x - 1)(2x + 1).

83. If 2x + 3 = 11, what is x²?

Solution
Correct: A
Subtract 3: 2x = 8 ⇒ x = 4 ⇒ x² = 16.

84. Simplify (x³ - x)/(x² - 1).

Solution
Correct: A
Factor: x(x² - 1)/(x² - 1) = x (x² ≠ 1).

85. Find the equation of the line with slope 2 through (1, 3).

Solution
Correct: A
Point-slope: y - 3 = 2(x - 1) ⇒ y = 2x + 1.

86. Expand (3x - 2)(x + 4).

Solution
Correct: A
FOIL: 3x² + 12x - 2x - 8 = 3x² + 10x - 8.

87. Solve 7x + 1 = 3x + 17.

Solution
Correct: A
Subtract 3x: 4x + 1 = 17. Subtract 1: 4x = 16 ⇒ x = 4.

88. If q(x) = x² - 4, find q(0).

Solution
Correct: A
Substitute: 0 - 4 = -4.

89. Simplify (x⁻³)(x³).

Solution
Correct: A
Product rule: x^(-3+3) = x⁰ = 1.

90. Find the y-intercept of 2x - 5y = 10.

Solution
Correct: A
Set x = 0: -5y = 10 ⇒ y = -2.

91. Evaluate (x² - 1)/(x - 1) when x = 0.

Solution
Correct: A
Substitute x = 0: (0 - 1)/(0 - 1) = (-1)/(-1) = 1.

92. Factor x² + 8x + 16.

Solution
Correct: A
Perfect square: x² + 8x + 16 = (x + 4)².

93. Solve x² + 9 = 25.

Solution
Correct: A
Subtract 9: x² = 16 ⇒ x = ±4.

94. If 5x - 2y = 8 and y = 4, find x.

Solution
Correct: A
Substitute y = 4: 5x - 8 = 8 ⇒ 5x = 16 ⇒ x = 16/5.

95. Simplify (2x⁻²)³.

Solution
Correct: A
Power of product: 2³x^(-2·3) = 8x⁻⁶.

96. What is the axis of symmetry of y = -x² + 4x - 3?

Solution
Correct: A
x = -b/(2a) = -4/(-2) = 2.

97. Solve 2(x - 1) = x + 3.

Solution
Correct: A
Expand: 2x - 2 = x + 3. Subtract x: x - 2 = 3 ⇒ x = 5.

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