10 questions · Form 4 Mathematics Bab 1: Quadratic Functions and Equations in One Variable
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Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.
1. Convert the equation (2x - 3)² = 25 into general quadratic form ax² + bx + c = 0.
Answer: A
Expand: 4x² - 12x + 9 = 25 => 4x² - 12x + 9 - 25 = 0 => 4x² - 12x - 16 = 0.
2. The diagram shows a quadratic graph with roots at x = -1 and x = 5. Which of the following equations could represent this graph?
Answer: B
If roots are x = -1 and x = 5, then f(x) = (x + 1)(x - 5) = x² - 4x - 5.
3. Given that the quadratic function f(x) = x² - bx + 16 has its axis of symmetry at x = 4, find the value of b.
Answer: A
Axis of symmetry x = --b2 × 1 = b2. Setting b2 = 4 yields b = 8.
4. Which graph correctly represents a quadratic function with a > 0 and c < 0?
Answer: C
a > 0 gives a U-shaped curve (opens upwards), and c < 0 means the y-intercept is negative (below the origin).
5. Find the roots of the quadratic equation x² - 5x + 6 = 0.
Answer: B
Factorising gives (x - 2)(x - 3) = 0. Therefore, the roots are x = 2 and x = 3.
6. Determine the coordinates of the minimum point of the function f(x) = x² - 6x + 5.
Answer: B
x = -b2a = --62 × 1 = 3. Substituting x = 3: f(3) = (3)² - 6(3) + 5 = 9 - 18 + 5 = -4. Minimum point is (3, -4).
7. Solve the quadratic equation 2x² - 7x + 3 = 0.
Answer: A
Factorising: (2x - 1)(x - 3) = 0 => 2x - 1 = 0 or x - 3 = 0. Roots are x = 12 and x = 3.
8. Which statement is TRUE regarding the graph of f(x) = -x² + 4x + 12?
Answer: C
Axis of symmetry x = -42 × -1 = 2. Maximum value = -(2)² + 4(2) + 12 = 16, and y-intercept is (0, 12).
9. How does the value of 'a' affect the graph of f(x) = ax² + bx + c?
Answer: C
The sign of 'a' controls direction (up/down) and the magnitude of 'a' controls the width of the parabola.
10. What is the y-intercept of the quadratic function f(x) = 3x² - 5x - 8?
Answer: A
The y-intercept occurs when x = 0. Substituting x = 0 gives f(0) = -8. Thus, the point is (0, -8).