# 中四 數學試卷 (F4 Maths Past Paper)

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maths Half_Yearly_Exam_Paper_1_Q_A

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## 中四數學試卷 PDF 下載

Secondary 4
INSTRUCTIONS
Belilios Public School
Half-Yearly Examination, 2015-2016
MATHEMATICS Compulsory Part
2. This paper consists of THREE sections, A(1), A(2) and B.
Time Allowed: 1/2 hours
1. After the announcement of the start of the examination, you should first write your Name, Class Number
and Class in the spaces provided.
Maximum Marks: 105
Math Class: C / M
3. Attempt ALL questions in this paper. Write your answers in the spaces provided in this
5. Unless otherwise specified, all working must be clearly shown.
4. Graph paper and supplementary answer sheets will be supplied on request.
7. The diagrams in this paper are not necessarily drawn to scale.
6. Unless otherwise specified, numerical answers should be either exact or correct to 3 significant figures.
Answers written in the margins will not be marked.
(a) Solve the equation 92x-1= 27x+4.
(b) Solve the equation 5*-2 +5* - 130 = 0.
Answers written in the margins will not be marked.
Answers written in the margins will not be marked.
13. If a and are the roots of the equation 2x² − 3x + 1 = 0, find
(a) the value of a² + B
(b) a quadratic equation in x whose roots are o + 2 and ß² + 2.
Answers written in the margins will not be marked.
Answers written in the margins will not be marked.
SECTION B (35 marks)
Express z in the form of a + bi, where a, b are real numbers.
If z is a real number, find
(i) the value of k,
where k is a real number.
Answers written in the margins will not be marked.
Answers written in the margins will not be marked.
In Figure 4, L₁ is the straight line passing through A(-3, 2)
and B(2, 7). L₂ is perpendicular to L₁ and passes through B
and C. L3 is a horizontal line which intersects L₁ and L2 at
A and C respectively.
(a) Find the equation of L₂ in the general form, and the
coordinates of C.
(b) D is a point on the line segment AC such that
area of AABD = 4 × area of ACBD.
(i) Find the coordinates of D.
(ii) Find the equation of BD in the general form.
Answers written in the margins will not be marked.
Answers written in the margins will not be marked.
Answers written in the margins will not be marked.
Answers written in the margins will not be marked.
As shown in Figure 5, in AABC, ZABC = 90°, AB = 8 cm and BC = 6 cm. The rectangle BDEF is
inscribed in AABC. Let DB = EF = x cm. Let the area of rectangle BDEF be S cm².
(a) Express the length of DE in terms of x.
(b) Express Sin terms of x.
(c) A student thinks that the area of BDEF is maximum when D is the mid-point of AB.
Answers written in the margins will not be marked.
Answers written in the margins will not be marked.
Answers written in the margins will not be marked.
Answers written in the margins will not be marked.
In a city, the number N of babies born in the t-th year after 2008 can be represented by the
following formula:
N = a - b(0.9)', where a and b are constants.
The number of babies born in 2010 was 43 480. The number of babies born in 2011 was 44 452.
(a) Find the values of a and b.
Find the number of babies born in 2013.
(c) In 2016, the government of the city will give a subsidy of \$5 000 to each baby
born. Will the
total amount of subsidy in 2016 exceed \$200 000 000? Explain your answer.
(Give the answers correct to the nearest integer if necessary.)
Answers written in the margins will not be marked.
END OF PAPER
Answers written in the margins will not be marked.
Answers written in the margins will not be marked.
Belilios Public School
Half-Yearly Examination, 2015-2016
S4 Mathematics Compulsory Part Marking Scheme
SECTION A(1) (35 marks)
1. Make y subject of the formula z =
2. Simplify
z(x - y) = xy
xz = zy + xy
xz = y(x + z)
4-1 (- 9)-3
1M for collecting like
IM for √√a = an
1M for a xa" = a
can be omitted
Answers written in the margins will not be marked.
SECTION A(1)
1. Make y the subject of the formula _z =
Answers written in the margins will not be marked.
(a) x²-x²y + 18x²,
(b) x²-x²y + 18x2² - x +y -18.
x² - xy + 18x²
= x²(x -y +18)
(b) x²-x²y + 18x2²-
18x² − x +y −18
= x²(x-y+18) - (x-y+18)
= (x² − 1)(x-y+18)
= (x+1)(x-1)(x − y +18)
(a) Selling price of the vase = \$280(1-40%)
(b) Cost = \$280:(1+75%)
As cost of the vase < selling price of the vase,
There will be a gain after selling the vase.
4. The marked price of a vase is \$280. The vase is sold at a discount of 40% of the marked price.
(a) Find the selling price of the vase.
(b) If the marked price of the vase is 75% above its cost, determine whether there will be a gain or
1M (use (a))
5. Consider the graph of the quadratic function y = −3(x+5)² +7.
(a) State the direction of opening.
(b) Find coordinates of the vertex.
(c) Find the y-intercept of the graph.
(a) It opens downwards.
(b) Coordinates of the vertex are (-5,7)
(c) When x = 0, y = -68
The y-intercept = -68
(b) 2(x + 1)(x − 1) = x
(a) x²-12x - 45 = 0
(a) x² -12x-45= 0
(x −15)(x + 3) = 0
x = 15 or −3
(b) 2(x+1)(x - 1) = x
2(x²-1) = x
- (-1) ± √(-1)² - 4(2)(−2)
1± √√17
1M can be omitted
It is given that f(x) = ax² + 24x + 7 and ƒ(-1) = −13.
(b) If g(x) = f(-/-)₁
Find the value of a.
(i) find the algebraic representation of g(x).
(ii) Determine the nature of roots of the equation g(x) = 0.
a (-1)² + 24(-1) + 7 = -13
= x² + 12x +7
(ii) A = 12²-4(1)(7)
There are two distinct real roots.
It is given that the quadratic equation x(x-7)= k-7 has real roots.
(a) Find the range of values of k.
Solve the equation when k is the smallest positive integer in (a).
x² - 7x+7-k=0
" The quadratic equation x(x-7)=k-7 has real roots.
(-7)² - 4(1)(7-k) ≥0
49-28+4k ≥0
.". The range of values of k is k≥--
(b) When k is the smallest positive integer in (a), k = 1.
When k = 1, the corresponding quadratic equation is
x² -7x+7-1=0
x² - 7x+6=0
(x-1)(x-6)=0
x=1 or x = 6
1M for A≥0 +1A
SECTION A(2) (35 marks)
In Figure 1, the straight line L₁: y=mx+12 which passes through (2, 4), has the same x-intercept
with another straight line L₂. It is given that the y-intercept of the straight line L₂ is 1.
(a) Find the value of m.
Find the equation of L₂.
(c) Mary claims that L, is not perpendicular to L₂.
L₁ passes through (2, 4).
... By substituting (2, 4) into y = mx + 12, we have....
4 = m(2) + 12
(b) By substituting y = 0 into y = -4x + 12, we have
The x-intercept of L₁ is 3.
L₁ has the same x-intercept with L₂.
L₂ passes through (3, 0).
The equation of L₂ is
Slope of L₁ = -4.
Slope of L2
y-0= -(x-3)
Slope of L₁ × slope of L2
Therefore the two lines are not perpendicular.
Mary's claim is agreed.
1M either one
1 for correct explanation
10. Figure 2 shows the graph of y = -x² + bx + c. Find
the values of b and c,
the axis of symmetry of the graph,
the maximum value of y.
(a) From the graph,
(b) Let A and B be the points (-1, 2) and (0, 2) respectively.
Coordinates of the mid-point of AB =
y-intercept = 2
The graph passes through (−1, 2).
2 = −(−1)² + b(-1) + 2
(c) By substituting x =
The axis of symmetry is x =
The axis of symmetry passes through the mid-point of AB.
x=-(-)²-(--)) + ²
into y = -x² - x + 2, we have
The maximum value of y is
The coordinates of the vertex of the graph are
y=-x² + bx + c
1M (or use completing square)
11. Figure 3 is the graph of y=1.5*.
(c) Plot y =
(a) Using the graph above to find the approximate values of the following expressions.
(b) Solve the following equation graphically. (Give your answers correct to the nearest 0.2.)
for -4≤ x ≤ 4 on the Figure 3.
√1.58 = 1.55
From the graph, when x=1.6, y = 1.9 (corr. to the nearest 0.1).
√1.58 = 1.9
اليدين
From the graph, when x = -0.6, y = 0.8 (corr. to the nearest 0.1).
(c) correct shape
From the graph, the solution for 1.5* = 4 is 3.4 (corr. to the nearest 0.2)
With correct y-intercept
(a) Solve the equation 9²x-
(b) Solve the exponential equation. 5-2 +5* - 130=0.
(a) 9²x-¹=27x+4
32(2x-1)= 33(x +
4x - 2 = 3x + 12
(b) 5-2 +5 -130 = 0.
5.52 +5 = 130
5* (5−²+1)=130
13. If a and are the roots of the equation 2x² – 3x + 1 = 0, find
(a) the value of a² + ß²,
(b) a quadratic equation in x whose roots are a² + 2 and ß² + 2.
13. From the equation 2x²-3x+1=0, we have
a² + B² = (a + B)² - 2aß
Sum of roots = (a² + 2) + (ß² + 2)
=a² + B² +4
Product of roots = (a² +2)(ß² +2)
= (aß)² +2(a² + ß²) + 4
..The required equation is
i.e. 4x² -21x+27= 0.
Answers written in the margins will not be marked.
3. Factorize
(a) x²-x²y + 18x²,
(b) _x³−x²y + 18x² − x +y −18.
4. The marked price of a vase is \$280. The vase is sold at a discount of 40% of the marked price.
(a) Find the selling price of the vase.
If the marked price of the vase is 75% above its cost, determine whether there will be a gain
Answers written in the margins will not be marked.
SECTION B (35 marks)
14. Let z =
Express z in the form of a + bi, where a, b are real numbers.
If z is a real number, find
(i) the value of k,
where k is a real number.
5+ki+10i+2ki²
1² - (2i)²
5+ (10+ k)i +2k(-1)
z is a real number.
15. In Figure 4, L₁ is the straight line passing through A(-3, 2) and
B(2, 7). L₂ is perpendicular to L₁ and passes through B and C.
L3 is a horizontal line which intersects L₁ and L2 at A and C
respectively.
(a) Find the equation of L₂ in the general form, and the
coordinates of C
(b) D is a point on the line segment AC such that
area of AABD = 4 × area of ACBD.
(i) Find the coordinates of D.
(ii) Find the equation of BD in the general form.
15(a) Slope of L₁
Slope of L₂
The equation of L₂ is
Let (a, 2) be the coordinates of C.
By substituting (a, 2) into x+y-9=0, we have
The coordinates of C are (7, 2).
Let (d, 2) be the coordinates of D.
AABD and ACBD have the same height.
Area of CBD DC
.. The coordinates of D are (5,2).
The equation of BD is
y-2=-=(x-5)
3y-6=-5x+25
As shown in Figure 5, in AABC, ZABC = 90°, AB = 8 cm and BC = 6 cm. The rectangle BDEF is
inscribed in AABC. Let DB = EF = x cm. Let the area of rectangle BDEF be S cm².
(a) Express the length of DE in terms of x.
(b) Express S in terms of x.
(c) A student thinks that the area of BDEF is maximum when D is the mid-point of AB.
(c) S= 7x(8 - x)
(x²+6x) cm²
=-²/(x-4)² +12
(b) The area S of the rectangle BDEF = BD × DE
= -³2 (x² − 8x + 4²) + ²/(4²)
The maximum value of S is 12 when x = 4.
(corr. sides, As)
(x-4)² ≤0 for all x, ..S≤ 12 for all x.
The area of rectangle BDEF is maximum when D is the mid-point of AB
The student is correct.
17 In a city, the number N of babies born in the t-th year after 2008 can be represented by the
following formula:
N = a - b(0.9)', where a and b are constants.
The number of babies born in 2010 was 43 480. The number of babies born in 2011 was 44 452.
(a) Find the values of a and b.
(b) Find the number of babies born in 2013.
In 2016, the government of the city will give a subsidy of \$5 000 to each baby born. Will the
total amount of subsidy in 2016 exceed \$200 000 000? Explain your answer.
(Give the answers correct to the nearest integer if necessary.)
17(a) In 2010, t = 2010 - 2008 = 2, and N = 43 480.
43 480 = a - b(0.9)²
In 2011, t = 2011 - 2008 = 3, and N = 44 452.
44 452 = ab(0.9)³
44 452 a 0.729b............
972 = 0.081b
Substituting b= 12 000 into (i), we have
43 480 a 0.81(12 000)
(ii) - (i):
(b) From (a), N = 53 200 12 000(0.9)¹.
In 2013, t = 2013 - 2008 = 5, and
N = 53 200 12 000(0.9)³
= 46 114, cor. to the nearest integer
The required number of babies is 46 114.
In 2016, t = 2016 - 2008 = 8, and
N = 53 200 12 000(0.9)⁹
Total amount of subsidy
= \$5 000(48 034)
= \$240 170 000
= 48 034, cor. to the nearest integer
\$240 170 000 > \$200 000 000
The total amount of subsidy will exceed \$200 000 000.
END OF PAPER
Answers written in the margins will not be marked.
Consider the graph of the quadratic function y = −3(x+5)² +7.
(a) State the direction of opening.
(b) Find coordinates of the vertex.
(c) Find the y-intercept of the graph.
(a) x² - 12x - 45 = 0
(b) 2(x + 1)(x − 1) = x
Answers written in the margins will not be marked.
Answers written in the margins will not be marked.
It is given that f(x) = ax² + 24x + 7 and ƒ(-1) = −13.
(a) Find the value of a.
(b) It is given that g(x) = f
Find the algebraic representation of g(x).
Determine the nature of the roots of the equation g(x) = 0.
Answers written in the margins will not be marked.
Answers written in the margins will not be marked.
It is given that the quadratic equation_x(x-7)= k-7 has real roots.
(a) Find the range of values of k.
(b) Solve the equation when k is the smallest positive integer in (a).
Answers written in the margins will not be marked.
Answers written in the margins will not be marked.
SECTION A(2) (35 marks)
In Figure 1, the straight line L₁: y=mx+12 which passes through (2, 4), has the same x-intercept
with another straight line L₂. It is given that the y-intercept of the straight line L2 is 1.
(a) Find the value of m.
Find the equation of L2.
Mary claims that L, is not perpendicular to L2.
Answers written in the margins will not be marked.
Answers written in the margins will not be marked.
10. Figure 2 shows the graph of y = -x²+bx+c. Find
the values of b and c.
the axis of symmetry of the graph,
the maximum value of y.
(-1,2)X 2 y = -x² + bx + C
Answers written in the margins will not be marked.
Answers written in the margins will not be marked.
11. Figure 3 is the graph of y = 1.5*.
(i) √√√₁.
(a) Using the graph above to find the approximate values of the following expressions.