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Secondary 4 Elementary Mathematics Algebra Functions Quiz
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Questions
Secondary 4 Elementary Mathematics Quiz - Algebra Functions
Name: _________________________ Class: _________________________ Date: _________________________ Score: _____ / 40
Duration: 45 minutes Total Marks: 40
Instructions:
- Answer ALL questions.
- Show all working clearly.
- Marks are indicated in brackets [ ].
- Calculators are allowed unless stated otherwise.
- Where graphs are required, use the graph paper provided.
Section A: Functions and Notation (Questions 1–5)
[10 marks]
1. Given the function f(x) = 3x² − 2x + 5, find: (a) f(2) [1] (b) f(−1) [1]
(a) _________________________
(b) _________________________
2. The function g is defined as g(x) = 2x − 7. (a) Find g(4). [1] (b) Solve g(x) = 11. [1]
(a) _________________________
(b) _________________________
3. Given h(x) = (x + 3)(x − 1), express h(x) in the form x² + px + q, stating the values of p and q. [2]
p = _________, q = _________
4. The function f is defined by f(x) = 4 − x². (a) Find f(0). [1] (b) Find the values of x for which f(x) = 0. [2]
(a) _________________________
(b) _________________________
5. A function k is given by k(x) = ax + b, where a and b are constants. Given that k(1) = 5 and k(3) = 13, find the values of a and b. [3]
a = _________, b = _________
Section B: Quadratic Functions and Graphs (Questions 6–12)
[14 marks]
6. Sketch the graph of y = (x − 2)² + 1, showing clearly the coordinates of the turning point and the y-intercept. [3]
Turning point: ( ____ , ____ ) y-intercept: ( ____ , ____ )
Sketch on graph paper provided.
7. The quadratic function y = −(x + 1)² + 4 is given. (a) Write down the coordinates of the maximum point. [1] (b) Find the x-intercepts of the graph. [2]
(a) Maximum point: ( ____ , ____ )
(b) x = ________ or x = ________
8. Express y = x² − 6x + 5 in the form y = (x − p)² + q. Hence write down the minimum value of y and the value of x at which it occurs. [3]
y = (x − ____)² + ____
Minimum value of y = ________ when x = ________
9. The graph of y = (x − a)(x − b) cuts the x-axis at x = 2 and x = −3. (a) Write down the values of a and b. [1] (b) Find the equation of the axis of symmetry. [1]
(a) a = ________, b = ________
(b) Axis of symmetry: x = ________
10. A quadratic function has a minimum point at (3, −4) and passes through the point (5, 0). Find the equation of the function in the form y = a(x − p)² + q. [3]
y = ____ (x − ____)² − ____
11. The graph of y = x² + 2x − 8 is drawn. (a) Find the coordinates of the points where the graph crosses the x-axis. [2] (b) Find the coordinates of the turning point. [2]
(a) ( ____ , ____ ) and ( ____ , ____ )
(b) Turning point: ( ____ , ____ )
12. Solve the quadratic equation 2x² − 5x − 3 = 0 by factorisation. [3]
x = ________ or x = ________
Section C: Power Functions and Exponential Functions (Questions 13–16)
[8 marks]
13. The graph of y = ax³ passes through the point (2, 24). Find the value of a. [2]
a = ________
14. Sketch the graph of y = 4/x for x > 0, showing at least two points on the curve. [2]
*Sketch on graph paper provided.*
Points: ( ____ , ____ ) and ( ____ , ____ )
15. The function y = 3 × 2ˣ is given. (a) Find the value of y when x = 0. [1] (b) Find the value of y when x = 3. [1]
(a) y = ________
(b) y = ________
16. The graph of y = k × 3ˣ passes through the point (2, 36). Find the value of k. [2]
k = ________
Section D: Gradient of Curves and Applications (Questions 17–20)
[8 marks]
17. The curve y = x² + 3x − 1 is drawn. By drawing a tangent at the point where x = 2, estimate the gradient of the curve at this point. [2]
Estimated gradient = ________
18. A stone is thrown upwards. Its height, h metres, after t seconds is given by h = 20t − 5t². (a) Find the height of the stone when t = 1. [1] (b) Find the time when the stone hits the ground (h = 0). [2]
(a) h = ________ m
(b) t = ________ s
19. The graph of y = x³ − 3x + 2 is drawn for −2 ≤ x ≤ 2. (a) Find the value of y when x = −1. [1] (b) By drawing a tangent at x = 1, estimate the gradient of the curve at this point. [2]
(a) y = ________
(b) Estimated gradient = ________
20. The cost, 250. [2]
(a) $________
(b) x = ________
END OF QUIZ
Check your answers carefully.
Answers
Secondary 4 Elementary Mathematics Quiz - Algebra Functions
ANSWER KEY AND MARKING SCHEME
Total Marks: 40
Section A: Functions and Notation (Questions 1–5)
1. f(x) = 3x² − 2x + 5 (a) f(2) = 3(2)² − 2(2) + 5 = 3(4) − 4 + 5 = 12 − 4 + 5 = 13 [1] (b) f(−1) = 3(−1)² − 2(−1) + 5 = 3(1) + 2 + 5 = 3 + 2 + 5 = 10 [1]
2. g(x) = 2x − 7 (a) g(4) = 2(4) − 7 = 8 − 7 = 1 [1] (b) 2x − 7 = 11 → 2x = 18 → x = 9 [1]
3. h(x) = (x + 3)(x − 1) Expand: h(x) = x² − x + 3x − 3 = x² + 2x − 3 p = 2, q = −3 [2] Award 1 mark for correct expansion, 1 mark for identifying p and q.
4. f(x) = 4 − x² (a) f(0) = 4 − 0² = 4 [1] (b) 4 − x² = 0 → x² = 4 → x = 2 or x = −2 [2] Award 1 mark for setting equation to zero, 1 mark for both solutions.
5. k(x) = ax + b k(1) = a(1) + b = 5 → a + b = 5 ... (1) k(3) = a(3) + b = 13 → 3a + b = 13 ... (2) (2) − (1): 2a = 8 → a = 4 Substitute into (1): 4 + b = 5 → b = 1 a = 4, b = 1 [3] Award 1 mark for each equation, 1 mark for solving correctly.
Section B: Quadratic Functions and Graphs (Questions 6–12)
6. y = (x − 2)² + 1
- Turning point: (2, 1) [1]
- y-intercept: when x = 0, y = (0 − 2)² + 1 = 4 + 1 = 5 → (0, 5) [1]
- Sketch: U-shaped parabola, vertex at (2, 1), passing through (0, 5) [1] Award 1 mark for correct turning point, 1 mark for y-intercept, 1 mark for correct shape and position.
7. y = −(x + 1)² + 4 (a) Maximum point: (−1, 4) [1] (b) For x-intercepts: −(x + 1)² + 4 = 0 → (x + 1)² = 4 → x + 1 = ±2 → x = 1 or x = −3 x = 1 or x = −3 [2] Award 1 mark for setting equation to zero, 1 mark for both solutions.
8. y = x² − 6x + 5 Complete the square: x² − 6x = (x − 3)² − 9 So y = (x − 3)² − 9 + 5 = (x − 3)² − 4 y = (x − 3)² − 4 [2] Minimum value of y = −4 when x = 3 [1] Award 1 mark for completing square correctly, 1 mark for simplified form, 1 mark for minimum value and x-value.
9. y = (x − a)(x − b), x-intercepts at x = 2 and x = −3 (a) a = 2, b = −3 (or vice versa) [1] (b) Axis of symmetry: x = (2 + (−3))/2 = −1/2 x = −½ [1]
10. Minimum point at (3, −4), passes through (5, 0) Form: y = a(x − 3)² − 4 Substitute (5, 0): 0 = a(5 − 3)² − 4 → 0 = a(4) − 4 → 4a = 4 → a = 1 y = 1(x − 3)² − 4 or y = (x − 3)² − 4 [3] Award 1 mark for correct form, 1 mark for substituting point, 1 mark for finding a.
11. y = x² + 2x − 8 (a) Factorise: (x + 4)(x − 2) = 0 → x = −4 or x = 2 Points: (−4, 0) and (2, 0) [2] Award 1 mark for factorisation, 1 mark for both coordinates. (b) Complete the square: y = (x + 1)² − 1 − 8 = (x + 1)² − 9 Turning point: (−1, −9) [2] Award 1 mark for completing square, 1 mark for coordinates.
12. 2x² − 5x − 3 = 0 Factorise: (2x + 1)(x − 3) = 0 2x + 1 = 0 → x = −½ x − 3 = 0 → x = 3 x = −½ or x = 3 [3] Award 1 mark for correct factorisation, 1 mark for each solution.
Section C: Power Functions and Exponential Functions (Questions 13–16)
13. y = ax³, passes through (2, 24) 24 = a(2)³ → 24 = 8a → a = 3 [2] Award 1 mark for substitution, 1 mark for correct value.
14. y = 4/x for x > 0 Points: when x = 1, y = 4 → (1, 4) When x = 2, y = 2 → (2, 2) When x = 4, y = 1 → (4, 1) Sketch: decreasing curve in first quadrant, asymptotic to axes. [2] Award 1 mark for at least two correct points, 1 mark for correct shape.
15. y = 3 × 2ˣ (a) When x = 0: y = 3 × 2⁰ = 3 × 1 = 3 [1] (b) When x = 3: y = 3 × 2³ = 3 × 8 = 24 [1]
16. y = k × 3ˣ, passes through (2, 36) 36 = k × 3² → 36 = k × 9 → k = 4 [2] Award 1 mark for substitution, 1 mark for correct value.
Section D: Gradient of Curves and Applications (Questions 17–20)
17. y = x² + 3x − 1 at x = 2 At x = 2: y = 4 + 6 − 1 = 9, point is (2, 9) Draw tangent at (2, 9). Gradient ≈ (change in y)/(change in x) from tangent. Using derivative: dy/dx = 2x + 3, at x = 2, gradient = 7. Estimated gradient = 7 (accept 6.5 to 7.5 depending on tangent accuracy) [2] Award 1 mark for drawing tangent, 1 mark for reasonable gradient estimate.
18. h = 20t − 5t² (a) When t = 1: h = 20(1) − 5(1)² = 20 − 5 = 15 m [1] (b) h = 0: 20t − 5t² = 0 → 5t(4 − t) = 0 → t = 0 or t = 4 Stone hits ground at t = 4 s [2] Award 1 mark for factorisation, 1 mark for correct non-zero time.
19. y = x³ − 3x + 2 (a) When x = −1: y = (−1)³ − 3(−1) + 2 = −1 + 3 + 2 = 4 [1] (b) At x = 1: y = 1 − 3 + 2 = 0, point is (1, 0) Draw tangent at (1, 0). Using derivative: dy/dx = 3x² − 3, at x = 1, gradient = 0. Estimated gradient = 0 (accept −0.5 to 0.5) [2] Award 1 mark for drawing tangent, 1 mark for reasonable estimate.
20. C = 100 + 2x + 0.1x² (a) When x = 10: C = 100 + 2(10) + 0.1(100) = 100 + 20 + 10 = $130 [1] (b) 250 = 100 + 2x + 0.1x² → 0.1x² + 2x − 150 = 0 Multiply by 10: x² + 20x − 1500 = 0 Factorise: (x + 50)(x − 30) = 0 → x = −50 or x = 30 Since x > 0, x = 30 [2] Award 1 mark for setting up equation, 1 mark for solving and selecting positive solution.
END OF ANSWER KEY