Cambridge IGCSE · Thinka-original Practice Paper

2024 Cambridge IGCSE Mathematics (0580) Practice Paper with Answers

Thinka Nov 2024 (V1) Cambridge International A Level-Style Mock — Mathematics (0580)

200 marks240 mins2024
An original Thinka practice paper modelled on the structure and difficulty of the Nov 2024 (V1) Cambridge International A Level Mathematics (0580) paper. Not affiliated with or reproduced from Cambridge.

Paper 2 (Extended)

Answer all questions. Use a calculator where appropriate. Show all working clearly.
23 Question · 69 marks
Question 1 · Short Answer
3 marks
Find the \(x\)-coordinates of the points of intersection of the curve \(y = x^2 - 3x - 11\) and the straight line \(y = 2x + 3\).
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Worked solution

To find the points of intersection, set the two equations equal to each other:
\[x^2 - 3x - 11 = 2x + 3\]
Rearrange to form a quadratic equation equal to zero:
\[x^2 - 3x - 2x - 11 - 3 = 0\]
\[x^2 - 5x - 14 = 0\]
Factorise the quadratic expression:
\[(x - 7)(x + 2) = 0\]
This gives:
\[x = 7 \quad \text{and} \quad x = -2\]

Marking scheme

M1 for setting the expressions equal: \(x^2 - 3x - 11 = 2x + 3\)
M1 for writing in the form \(x^2 - 5x - 14 = 0\) (or equivalent)
A1 for both solutions: \(-2\) and \(7\)
Question 2 · Short Answer
3 marks
Solve the equation:
\[\frac{6}{x-1} - \frac{4}{x} = 1\]
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Worked solution

Multiply the entire equation by the common denominator \(x(x-1)\):
\[6x - 4(x-1) = 1 \cdot x(x-1)\]
Expand both sides:
\[6x - 4x + 4 = x^2 - x\]
\[2x + 4 = x^2 - x\]
Rearrange into standard quadratic form:
\[x^2 - 3x - 4 = 0\]
Factorise the quadratic equation:
\[(x - 4)(x + 1) = 0\]
This gives:
\[x = 4 \quad \text{or} \quad x = -1\]

Marking scheme

M1 for eliminating denominators correctly: \(6x - 4(x-1) = x(x-1)\) (or equivalent)
M1 for rearranging to standard quadratic form: \(x^2 - 3x - 4 = 0\)
A1 for \(x = 4\) and \(x = -1\)
Question 3 · Short Answer
3 marks
Simplify fully:
\[\frac{2x^2 - 5x - 3}{4x^2 - 1}\]
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Worked solution

Factorise the numerator:
\[2x^2 - 5x - 3 = (2x + 1)(x - 3)\]
Factorise the denominator using the difference of two squares:
\[4x^2 - 1 = (2x - 1)(2x + 1)\]
Now write as a simplified fraction by cancelling the common factor \((2x + 1)\):
\[\frac{(2x+1)(x-3)}{(2x-1)(2x+1)} = \frac{x-3}{2x-1}\]

Marking scheme

M1 for factorising the numerator: \((2x + 1)(x - 3)\)
M1 for factorising the denominator: \((2x - 1)(2x + 1)\)
A1 for the final simplified fraction: \(\frac{x-3}{2x-1}\)
Question 4 · Short Answer
3 marks
Find the \(n\)-th term of the sequence:
\[4, \; 11, \; 22, \; 37, \; 56, \; \dots\]
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Worked solution

Find the first and second differences of the sequence:
Terms: \(4, \quad 11, \quad 22, \quad 37, \quad 56\)
First differences: \(7, \quad 11, \quad 15, \quad 19\)
Second differences: \(4, \quad 4, \quad 4\)
Since the second difference is constant, the sequence is quadratic. The coefficient of \(n^2\) is half of the second difference: \(a = \frac{4}{2} = 2\).
Subtract \(2n^2\) from each term:
For \(n=1\): \(4 - 2(1)^2 = 2\)
For \(n=2\): \(11 - 2(2)^2 = 3\)
For \(n=3\): \(22 - 2(3)^2 = 4\)
For \(n=4\): \(37 - 2(4)^2 = 5\)
The remaining linear sequence is \(2, 3, 4, 5, \dots\), which has the \(n\)-th term of \(n + 1\).
Combining these gives the complete \(n\)-th term: \(2n^2 + n + 1\).

Marking scheme

M1 for finding the second difference is 4 (or establishing the \(2n^2\) term)
M1 for attempting to find the linear part by subtracting \(2n^2\) from terms or using simultaneous equations
A1 for the correct expression: \(2n^2 + n + 1\)
Question 5 · Short Answer
3 marks
Solve the equation:
\[27^{2x - 1} = \left(\frac{1}{9}\right)^{x - 4}\]
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Worked solution

Express both bases as powers of 3:
\[27 = 3^3 \implies 27^{2x - 1} = (3^3)^{2x - 1} = 3^{3(2x - 1)} = 3^{6x - 3}\]
\[\frac{1}{9} = 3^{-2} \implies \left(\frac{1}{9}\right)^{x - 4} = (3^{-2})^{x - 4} = 3^{-2(x - 4)} = 3^{-2x + 8}\]
Equating the indices since the bases are equal:
\[6x - 3 = -2x + 8\]
Solve for \(x\):
\[8x = 11\]
\[x = \frac{11}{8} = 1.375\]

Marking scheme

M1 for expressing both sides correctly as powers of 3: \(3^{3(2x-1)}\) and \(3^{-2(x-4)}\) (or equivalent)
M1 for equating the exponents: \(3(2x - 1) = -2(x - 4)\) (or equivalent)
A1 for \(\frac{11}{8}\) or \(1.375\)
Question 6 · Short Answer
3 marks
Calculate the value of:
\[\frac{(3.2 \times 10^{6}) \times (1.5 \times 10^{-3})}{8.0 \times 10^{-2}}\]
Give your answer in standard form.
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Worked solution

First, calculate the numerator:
\[(3.2 \times 1.5) \times 10^{6 + (-3)} = 4.8 \times 10^3\]
Next, divide by the denominator:
\[\frac{4.8 \times 10^3}{8.0 \times 10^{-2}} = \left(\frac{4.8}{8.0}\right) \times 10^{3 - (-2)}\]
\[= 0.6 \times 10^5\]
Convert to standard form:
\[= 6 \times 10^4\]

Marking scheme

M1 for simplifying the numerator to \(4.8 \times 10^3\) (or \(4800\))
M1 for dividing to find \(60000\) or \(0.6 \times 10^5\)
A1 for \(6 \times 10^4\) (or \(6.0 \times 10^4\))
Question 7 · Short Answer
3 marks
A sector of a circle has a radius of \(8\text{ cm}\) and a sector angle of \(135^\circ\). Calculate the perimeter of this sector. Give your answer correct to 3 significant figures.
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Worked solution

First, calculate the arc length of the sector:
\[\text{Arc length} = \frac{135}{360} \times 2 \times \pi \times 8\]
\[\text{Arc length} = \frac{3}{8} \times 16\pi = 6\pi \approx 18.85\text{ cm}\]
The perimeter of the sector is the arc length plus two radii:
\[\text{Perimeter} = \text{Arc length} + 2r = 6\pi + 2(8)\]
\[\text{Perimeter} = 18.85 + 16 = 34.85\text{ cm}\]
To 3 significant figures, this is \(34.8\text{ cm}\).

Marking scheme

M1 for formula or calculation for arc length: \(\frac{135}{360} \times 2 \times \pi \times 8\) (approx. \(18.8\))
M1 for adding two radii to their arc length: \(\text{arc length} + 16\)
A1 for \(34.8\) (accept answers in the range \([34.8, 34.9]\))
Question 8 · Short Answer
3 marks
A bag contains 5 red beads and 4 blue beads. Two beads are chosen at random from the bag, without replacement. Calculate the probability that the two beads are different colours.
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Worked solution

The total number of beads is \(5 + 4 = 9\).
There are two ways to get different colours:
1. First red, then blue:
\[P(\text{Red, then Blue}) = \frac{5}{9} \times \frac{4}{8} = \frac{20}{72}\]
2. First blue, then red:
\[P(\text{Blue, then Red}) = \frac{4}{9} \times \frac{5}{8} = \frac{20}{72}\]
Sum these probabilities to find the total probability of choosing different colours:
\[P(\text{Different}) = \frac{20}{72} + \frac{20}{72} = \frac{40}{72} = \frac{5}{9} \approx 0.556\]

Marking scheme

M1 for correct probability of one combined outcome, e.g., \(\frac{5}{9} \times \frac{4}{8}\) or \(\frac{4}{9} \times \frac{5}{8}\) (or \(\frac{20}{72}\))
M1 for adding both valid combinations: \(\left(\frac{5}{9} \times \frac{4}{8}\right) + \left(\frac{4}{9} \times \frac{5}{8}\right)\)
A1 for \(\frac{5}{9}\) (or equivalent fraction, or \(0.556\) or \(0.5555...\))
Question 9 · Short Answer
3 marks
Find the \(x\)-coordinates of the stationary points of the curve \(y = 2x^3 - 9x^2 - 24x + 7\). Write your answers in ascending order separated by a comma.
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Worked solution

To find the stationary points, we first differentiate \(y = 2x^3 - 9x^2 - 24x + 7\) with respect to \(x\):
\(\frac{dy}{dx} = 6x^2 - 18x - 24\)

At stationary points, \(\frac{dy}{dx} = 0\):
\(6x^2 - 18x - 24 = 0\)

Divide the entire equation by 6:
\(x^2 - 3x - 4 = 0\)

Factorise the quadratic expression:
\((x - 4)(x + 1) = 0\)

This gives \(x = -1\) and \(x = 4\).

In ascending order, the \(x\)-coordinates are \(-1, 4\).

Marking scheme

M1 for differentiating to get \(6x^2 - 18x - 24\) (at least two terms correct)
M1 for setting their derivative to 0 and attempting to solve the quadratic equation
A1 for both \(x = -1\) and \(x = 4\) (or -1, 4)
Question 10 · Short Answer
3 marks
Solve the simultaneous equations:
\(y = x - 3\)
\(x^2 + y^2 = 29\)
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Worked solution

Substitute \(y = x - 3\) into the second equation:
\(x^2 + (x - 3)^2 = 29\)
\(x^2 + x^2 - 6x + 9 = 29\)
\(2x^2 - 6x - 20 = 0\)

Divide the entire equation by 2:
\(x^2 - 3x - 10 = 0\)

Factorise the quadratic equation:
\((x - 5)(x + 2) = 0\)

So \(x = 5\) or \(x = -2\).

If \(x = 5\), then \(y = 5 - 3 = 2\).
If \(x = -2\), then \(y = -2 - 3 = -5\).

So the solutions are \(x = 5, y = 2\) and \(x = -2, y = -5\).

Marking scheme

M1 for substitution of \(y = x - 3\) to obtain a quadratic in \(x\): \(2x^2 - 6x - 20 = 0\) (or equivalent)
M1 for solving their quadratic to find \(x = 5\) and \(x = -2\)
A1 for both correct pairs of solutions: \(x = 5, y = 2\) and \(x = -2, y = -5\) (or written as coordinates)
Question 11 · Short Answer
3 marks
Simplify completely:
\(\frac{2x^2 - 5x - 3}{4x^2 - 1}\)
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Worked solution

Factorise the numerator:
\(2x^2 - 5x - 3 = (2x + 1)(x - 3)\)

Factorise the denominator as a difference of two squares:
\(4x^2 - 1 = (2x - 1)(2x + 1)\)

Simplify the fraction by cancelling the common factor \((2x + 1)\):
\(\frac{(2x + 1)(x - 3)}{(2x - 1)(2x + 1)} =
\frac{x - 3}{2x - 1}\)

Marking scheme

M1 for factorising numerator: \((2x + 1)(x - 3)\)
M1 for factorising denominator: \((2x - 1)(2x + 1)\)
A1 for final answer \(\frac{x - 3}{2x - 1}\) or equivalent fraction
Question 12 · Short Answer
3 marks
Find the equation of the line perpendicular to \(y = \frac{2}{3}x - 5\) that passes through the point \((4, 7)\). Give your answer in the form \(y = mx + c\).
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Worked solution

The gradient of the given line is \(m_1 = \frac{2}{3}\).

Since the lines are perpendicular, the product of their gradients is \(-1\):
\(m_2 = -\frac{1}{2/3} = -\frac{3}{2} = -1.5\)

The equation of the perpendicular line is \(y = -1.5x + c\).

Substitute the point \((4, 7)\) into this equation:
\(7 = -1.5(4) + c\)
\(7 = -6 + c\)
\(c = 13\)

Therefore, the equation of the line is \(y = -1.5x + 13\).

Marking scheme

M1 for finding perpendicular gradient = \(-1.5\) (or \(-\frac{3}{2}\))
M1 for substituting \((4, 7)\) into \(y = (their\ m)x + c\) to find \(c\)
A1 for \(y = -1.5x + 13\) (or \(y = -\frac{3}{2}x + 13\))
Question 13 · Short Answer
3 marks
Simplify completely:
\(\left( \frac{64x^6}{y^3} \right)^{-\frac{2}{3}}\)
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Worked solution

First, use the reciprocal property of negative indices:
\(\left( \frac{64x^6}{y^3} \right)^{-\frac{2}{3}} = \left( \frac{y^3}{64x^6} \right)^{\frac{2}{3}}\)

Now, apply the power of \(\frac{2}{3}\) to each component of the fraction:
- For the numerator: \((y^3)^{\frac{2}{3}} = y^{3 \times \frac{2}{3}} = y^2\)
- For the denominator:
\(64^{\frac{2}{3}} = (\sqrt[3]{64})^2 = 4^2 = 16\)
\((x^6)^{\frac{2}{3}} = x^{6 \times \frac{2}{3}} = x^4\)

Combining these, we get:
\(\frac{y^2}{16x^4}\)

Marking scheme

M1 for dealing with negative index or fractional index of 64 (e.g. \(16\) or \(\frac{1}{16}\) seen)
M1 for a correct power of \(x\) or \(y\) (e.g. \(x^4\) or \(y^2\) in a relevant position)
A1 for \(\frac{y^2}{16x^4}\) (or \(\frac{1}{16}x^{-4}y^2\))
Question 14 · Short Answer
3 marks
A bag contains 5 red balls and 3 blue balls. Two balls are selected at random from the bag, one after the other, without replacement. Find the probability that the two balls selected are of different colours. Give your answer as a fraction in its simplest form.
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Worked solution

The total number of balls is \(5 + 3 = 8\).

There are two ways to select balls of different colours:
1) Red first, then Blue:
\(P(\text{Red, Blue}) = \frac{5}{8} \times \frac{3}{7} = \frac{15}{56}\)

2) Blue first, then Red:
\(P(\text{Blue, Red}) = \frac{3}{8} \times \frac{5}{7} = \frac{15}{56}\)

Add the two probabilities together:
\(P(\text{different colours}) = \frac{15}{56} + \frac{15}{56} = \frac{30}{56} = \frac{15}{28}\)

Marking scheme

M1 for calculating the probability of one combination correctly, e.g. \(\frac{5}{8} \times \frac{3}{7}\)
M1 for adding the two appropriate products, e.g. \(\frac{5}{8} \times \frac{3}{7} + \frac{3}{8} \times \frac{5}{7}\)
A1 for \(\frac{15}{28}\) (or equivalent fraction, or \(0.536\) or \(0.5357...\))
Question 15 · Short Answer
3 marks
A cuboid has a horizontal rectangular base \(ABCD\) with \(AB = 8\text{ cm}\) and \(BC = 6\text{ cm}\). The vertical height of the cuboid is \(CG = 5\text{ cm}\). Calculate the angle between the diagonal line \(AG\) and the base \(ABCD\). Give your answer correct to 1 decimal place.
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Worked solution

The diagonal of the base, \(AC\), is calculated using Pythagoras' theorem in triangle \(ABC\):
\(AC = \sqrt{AB^2 + BC^2} = \sqrt{8^2 + 6^2} = \sqrt{64 + 36} = \sqrt{100} = 10\text{ cm}\)

The angle between the diagonal line \(AG\) and the base \(ABCD\) is the angle \(\angle GAC\).

In the right-angled triangle \(ACG\), \(CG = 5\text{ cm}\) (opposite side) and \(AC = 10\text{ cm}\) (adjacent side):
\(\tan(\angle GAC) = \frac{CG}{AC} = \frac{5}{10} = 0.5\)

\(\angle GAC = \tan^{-1}(0.5) \approx 26.565^\circ\)

To 1 decimal place, the angle is \(26.6^\circ\).

Marking scheme

M1 for \(AC^2 = 8^2 + 6^2\) or \(AC = 10\)
M1 for \(\tan(\theta) = \frac{5}{their\ AC}\) (or equivalent trigonometric ratio)
A1 for \(26.6\) (accept \(26.56...\))
Question 16 · Short Answer
3 marks
The perimeter of a sector of a circle with radius \(9\text{ cm}\) is \(25\text{ cm}\). Calculate the sector angle. Give your answer correct to 1 decimal place.
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Worked solution

The perimeter of a sector of a circle is made up of two radii and the arc length \(L\):
\(P = 2r + L\)
\(25 = 2(9) + L\)
\(25 = 18 + L\)
\(L = 7\text{ cm}\)

Now use the arc length formula to find the sector angle \(x\):
\(L = \frac{x}{360} \times 2\pi r\)
\(7 = \frac{x}{360} \times 2 \times \pi \times 9\)
\(7 = \frac{18\pi x}{360}\)
\(7 = \frac{\pi x}{20}\)
\(x = \frac{140}{\pi} \approx 44.563^\circ\)

To 1 decimal place, the sector angle is \(44.6^\circ\).

Marking scheme

M1 for finding arc length = \(25 - 2 \times 9\) or \(7\)
M1 for \(\frac{x}{360} \times 2 \times \pi \times 9 = their\ 7\)
A1 for \(44.6\) (accept \(44.56...\))
Question 17 · Short Answer
3 marks
A curve has the equation \(y = 2x^3 - 9x^2 - 24x + 7\). Find the coordinates of the local minimum point. Give your answer as an ordered pair \((x, y)\).
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Worked solution

To find the stationary points, we first find the derivative: \(\frac{dy}{dx} = 6x^2 - 18x - 24\). Set the derivative to 0: \(6x^2 - 18x - 24 = 0\) which simplifies to \(x^2 - 3x - 4 = 0\), and factorises to \((x - 4)(x + 1) = 0\). This gives \(x = 4\) or \(x = -1\). To determine which is the minimum, we use the second derivative: \(\frac{d^2y}{dx^2} = 12x - 18\). For \(x = 4\): \(\frac{d^2y}{dx^2} = 12(4) - 18 = 30 > 0\), which confirms a local minimum. Finding the corresponding \(y\)-value: \(y = 2(4)^3 - 9(4)^2 - 24(4) + 7 = 128 - 144 - 96 + 7 = -105\). Thus, the coordinates of the local minimum are \((4, -105)\).

Marking scheme

M1 for correctly differentiating to get at least two terms of \(6x^2 - 18x - 24\); M1 for setting \(6x^2 - 18x - 24 = 0\) and solving to find \(x = 4\); A1 for the correct coordinates \((4, -105)\).
Question 18 · Short Answer
3 marks
Solve the equation: \(\frac{3}{x+2} + \frac{1}{x-1} = 2\). Show all your working and give your answers correct to 2 decimal places.
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Worked solution

Multiply both sides of the equation by the common denominator \((x + 2)(x - 1)\) to get: \(3(x - 1) + 1(x + 2) = 2(x + 2)(x - 1)\). Expanding both sides yields: \(3x - 3 + x + 2 = 2(x^2 + x - 2)\), which simplifies to \(4x - 1 = 2x^2 + 2x - 4\). Rearranging into standard quadratic form gives: \(2x^2 - 2x - 3 = 0\). Applying the quadratic formula \(x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\) gives: \(x = \frac{2 \pm \sqrt{(-2)^2 - 4(2)(-3)}}{2(2)} = \frac{2 \pm \sqrt{28}}{4}\). Calculating the two solutions gives: \(x = \frac{2 + 5.2915}{4} \approx 1.82\) and \(x = \frac{2 - 5.2915}{4} \approx -0.82\).

Marking scheme

M1 for clearing fractions correctly to get \(3(x - 1) + (x + 2) = 2(x + 2)(x - 1)\); M1 for obtaining the simplified quadratic equation \(2x^2 - 2x - 3 = 0\); A1 for both correct answers \(1.82\) and \(-0.82\).
Question 19 · Short Answer
3 marks
Rearrange the formula to make \(p\) the subject: \(T = \frac{3p + 5}{2 - p}\).
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Worked solution

First, multiply both sides by \((2 - p)\) to eliminate the fraction: \(T(2 - p) = 3p + 5\). Expand the left-hand side: \(2T - Tp = 3p + 5\). Collect all terms containing \(p\) on one side and the rest on the other: \(2T - 5 = 3p + Tp\). Factorise \(p\) on the right-hand side: \(2T - 5 = p(3 + T)\). Divide both sides by \(3 + T\) to solve for \(p\): \(p = \frac{2T - 5}{T + 3}\).

Marking scheme

M1 for multiplying by \(2 - p\) to get \(T(2 - p) = 3p + 5\); M1 for collecting terms containing \(p\) on one side and factoring out \(p\) to get \(p(3 + T) = 2T - 5\); A1 for the correct final answer \(p = \frac{2T - 5}{T + 3}\) or equivalent.
Question 20 · Short Answer
3 marks
Find the coordinates of the points of intersection of the line \(y = 3x - 1\) and the curve \(y = 2x^2 - 5x + 5\).
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Worked solution

Set the two equations equal to each other to find the intersection points: \(3x - 1 = 2x^2 - 5x + 5\). Rearranging into standard quadratic form gives: \(2x^2 - 8x + 6 = 0\). Dividing the entire equation by 2 yields: \(x^2 - 4x + 3 = 0\). Factorising the quadratic gives: \((x - 1)(x - 3) = 0\), which means \(x = 1\) or \(x = 3\). Substituting these back into the linear equation \(y = 3x - 1\) gives the corresponding \(y\)-values: For \(x = 1\), \(y = 3(1) - 1 = 2\); For \(x = 3\), \(y = 3(3) - 1 = 8\). Thus, the points of intersection are \((1, 2)\) and \((3, 8)\).

Marking scheme

M1 for equating equations to form a quadratic, e.g. \(2x^2 - 8x + 6 = 0\); M1 for finding both \(x\)-values: \(x = 1\) and \(x = 3\); A1 for both correct coordinate pairs \((1, 2)\) and \((3, 8)\).
Question 21 · Short Answer
3 marks
Solve the simultaneous equations: \(x + y = 5\) and \(x^2 + y^2 = 17\).
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Worked solution

From the first equation, express \(y\) in terms of \(x\): \(y = 5 - x\). Substitute this into the second equation: \(x^2 + (5 - x)^2 = 17\). Expanding the bracket gives: \(x^2 + 25 - 10x + x^2 = 17\), which simplifies to \(2x^2 - 10x + 8 = 0\). Dividing by 2 gives: \(x^2 - 5x + 4 = 0\). Factorising gives: \((x - 1)(x - 4) = 0\), so \(x = 1\) or \(x = 4\). If \(x = 1\), then \(y = 5 - 1 = 4\). If \(x = 4\), then \(y = 5 - 4 = 1\). Thus, the solutions are \(x = 1, y = 4\) and \(x = 4, y = 1\).

Marking scheme

M1 for correctly substituting \(y = 5 - x\) into the quadratic equation; M1 for simplifying to a 3-term quadratic and solving to find two values of \(x\) (or \(y\)), e.g. 1 and 4; A1 for the correct solutions: \(x = 1, y = 4\) and \(x = 4, y = 1\).
Question 22 · Short Answer
3 marks
Simplify fully: \(\frac{2x^2 - 7x - 15}{x^2 - 25}\).
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Worked solution

First, factorise the numerator: \(2x^2 - 7x - 15 = 2x^2 - 10x + 3x - 15 = 2x(x - 5) + 3(x - 5) = (2x + 3)(x - 5)\). Next, factorise the denominator using the difference of two squares: \(x^2 - 25 = (x - 5)(x + 5)\). Now, divide the factorised forms and cancel the common factor \((x - 5)\): \(\frac{(2x + 3)(x - 5)}{(x - 5)(x + 5)} = \frac{2x + 3}{x + 5}\).

Marking scheme

M1 for factorising the numerator: \((2x + 3)(x - 5)\); M1 for factorising the denominator: \((x - 5)(x + 5)\); A1 for the correct fully simplified fraction \(\frac{2x + 3}{x + 5}\).
Question 23 · Short Answer
3 marks
A curve has the equation \(y = \frac{8}{x} + x^2\). Find the gradient of the curve at the point where \(x = 4\).
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Worked solution

First, rewrite the equation as: \(y = 8x^{-1} + x^2\). Differentiate with respect to \(x\) to find the gradient function: \(\frac{dy}{dx} = -8x^{-2} + 2x = -\frac{8}{x^2} + 2x\). To find the gradient at \(x = 4\), substitute \(x = 4\) into the derivative: \(\frac{dy}{dx} = -\frac{8}{4^2} + 2(4) = -\frac{8}{16} + 8 = -0.5 + 8 = 7.5\).

Marking scheme

M1 for writing the first term as \(8x^{-1}\) and attempting differentiation (at least one term correct); M1 for the correct derivative \(-8x^{-2} + 2x\); A1 for substituting \(x = 4\) to obtain \(7.5\) (or equivalent fraction).

Paper 4 (Extended)

Answer all questions. Show all necessary working clearly. Non-exact numerical answers should be correct to 3 significant figures.
10 Question · 130 marks
Question 1 · Structured Multi-Part
13 marks
The function \( f(x) \) is defined as \( f(x) = x^3 - 4x^2 - 2x + 8 \).

(a) Find the coordinates of the points where the curve \( y = f(x) \) intersects:
(i) the \( y \)-axis, [1]
(ii) the \( x \)-axis. [3]

(b) Find the coordinates of the turning points of the curve \( y = f(x) \), giving your answers correct to 3 significant figures. [5]

(c) Show that the equation \( x^3 - 4x^2 - 5x + 10 = 0 \) can be solved by finding the intersection of the curve \( y = f(x) \) with a straight line. State the equation of this straight line. [2]

(d) Use your answers from part (b) to find the range of values of \( k \) for which the equation \( f(x) = k \) has exactly three distinct real solutions. [2]
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Worked solution

(a)(i) When \( x = 0 \), \( y = 0^3 - 4(0)^2 - 2(0) + 8 = 8 \). So the \( y \)-intercept is \( (0, 8) \).
(ii) When \( y = 0 \), \( x^3 - 4x^2 - 2x + 8 = 0 \).
Factoring by grouping: \( x^2(x - 4) - 2(x - 4) = 0 \implies (x^2 - 2)(x - 4) = 0 \).
This gives \( x = 4 \) or \( x = \pm\sqrt{2} \approx \pm 1.414 \).
So the \( x \)-intercepts are \( (4, 0) \), \( (1.41, 0) \), and \( (-1.41, 0) \).

(b) To find the turning points, set \( f'(x) = 0 \):
\( f'(x) = 3x^2 - 8x - 2 = 0 \).
Using the quadratic formula:
\( x = \frac{-(-8) \pm \sqrt{(-8)^2 - 4(3)(-2)}}{2(3)} = \frac{8 \pm \sqrt{64 + 24}}{6} = \frac{8 \pm \sqrt{88}}{6} \).
\( x_1 = \frac{8 + 9.3808}{6} \approx 2.897 \)
\( x_2 = \frac{8 - 9.3808}{6} \approx -0.230 \).

Substitute these back into \( f(x) \) to find the \( y \)-coordinates:
For \( x \approx 2.897 \):
\( y = (2.897)^3 - 4(2.897)^2 - 2(2.897) + 8 \approx -7.051 \).
For \( x \approx -0.230 \):
\( y = (-0.230)^3 - 4(-0.230)^2 - 2(-0.230) + 8 \approx 8.236 \).
So the turning points are \( (2.90, -7.05) \) and \( (-0.230, 8.24) \).

(c) We are given \( x^3 - 4x^2 - 5x + 10 = 0 \).
We want to write this in terms of \( f(x) = x^3 - 4x^2 - 2x + 8 \):
\( (x^3 - 4x^2 - 2x + 8) - 3x + 2 = 0 \implies f(x) = 3x - 2 \).
So the straight line equation is \( y = 3x - 2 \).

(d) For the equation \( f(x) = k \) to have three distinct real solutions, the horizontal line \( y = k \) must intersect the curve at three distinct points. This occurs when \( k \) lies strictly between the \( y \)-coordinates of the two turning points:
\( -7.05 < k < 8.24 \).

Marking scheme

(a)(i) B1: For \( (0, 8) \).
(ii) M1: For attempting to factor the cubic by grouping or finding one root.
A1: For root \( x = 4 \).
A1: For roots \( x = \pm\sqrt{2} \) (or 1.41, -1.41).

(b) M1: For differentiating to get \( 3x^2 - 8x - 2 \).
M1: For setting derivative to 0 and solving using quadratic formula.
A1: For \( x \approx 2.90 \) and \( x \approx -0.230 \).
M1: For substituting at least one of their \( x \)-values into the original cubic function.
A1: For final coordinates \( (2.90, -7.05) \) and \( (-0.230, 8.24) \).

(c) M1: For equating \( x^3 - 4x^2 - 2x + 8 = mx + c \) and comparing coefficients to reach \( mx + c \).
A1: For \( y = 3x - 2 \).

(d) M1: For identifying that \( k \) must lie between the \( y \)-values of the turning points.
A1: For \( -7.05 < k < 8.24 \) (accept answers consistent with their turning points from part b).
Question 2 · Structured Multi-Part
13 marks
An athlete runs a distance of 12 km at an average speed of \( x \) km/h.
She then runs a further 15 km at an average speed of \( (x - 2) \) km/h.
The total time taken for the run is 3.5 hours.

(a) Write down an equation in terms of \( x \) for the total time taken and show that it simplifies to \( 7x^2 - 68x + 48 = 0 \). [4]

(b) Solve the equation \( 7x^2 - 68x + 48 = 0 \), giving your answers correct to 2 decimal places. [4]

(c) State, with a reason, which value of \( x \) is the only realistic average speed of the athlete. Calculate the total time taken for the second part of her run using this value, giving your answer in hours and minutes to the nearest minute. [3]

(d) Calculate the average speed of the athlete over the entire 27 km run. [2]
Show answer & marking scheme

Worked solution

(a) Time taken for the first part: \( t_1 = \frac{12}{x} \)
Time taken for the second part: \( t_2 = \frac{15}{x - 2} \)
Total time: \( \frac{12}{x} + \frac{15}{x - 2} = 3.5 \)
Multiply by \( x(x - 2) \) to clear fractions:
\( 12(x - 2) + 15x = 3.5x(x - 2) \)
\( 12x - 24 + 15x = 3.5(x^2 - 2x) \)
\( 27x - 24 = 3.5x^2 - 7x \)
Multiply the entire equation by 2 to clear decimals:
\( 54x - 48 = 7x^2 - 14x \)
Rearrange to standard quadratic form:
\( 7x^2 - 68x + 48 = 0 \) (Showed)

(b) Using the quadratic formula:
\( x = \frac{68 \pm \sqrt{(-68)^2 - 4(7)(48)}}{2(7)} \)
\( x = \frac{68 \pm \sqrt{4624 - 1344}}{14} \)
\( x = \frac{68 \pm \sqrt{3280}}{14} \)
\( x \approx \frac{68 \pm 57.271}{14} \)
\( x_1 = \frac{125.271}{14} \approx 8.948 \implies 8.95 \)
\( x_2 = \frac{10.729}{14} \approx 0.766 \implies 0.77 \)

(c) If \( x = 0.77 \) km/h, the speed for the second part is \( x - 2 = 0.77 - 2 = -1.23 \) km/h, which is impossible. Thus, \( x = 8.95 \) km/h is the only realistic speed.
Time taken for the second part is:
\( t_2 = \frac{15}{8.948 - 2} = \frac{15}{6.948} \approx 2.1589 \) hours.
Converting to minutes: \( 0.1589 \times 60 \approx 9.53 \) minutes.
So, the time is 2 hours and 10 minutes.

(d) Average speed over the entire run:
\( \text{Total Distance} = 12 + 15 = 27 \) km.
\( \text{Total Time} = 3.5 \) hours.
\( \text{Average Speed} = \frac{27}{3.5} = 7.714 \approx 7.71 \) km/h.

Marking scheme

(a) M1: For writing an expression for time: \( \frac{12}{x} \) or \( \frac{15}{x-2} \).
M1: For the equation \( \frac{12}{x} + \frac{15}{x-2} = 3.5 \).
M1: For algebraically expanding and attempting to clear fractions.
A1: For successfully showing the given quadratic equation with intermediate steps.

(b) M1: For correct substitution into the quadratic formula.
B1: For \( \sqrt{3280} \) or \( 57.27... \).
A1: For \( x = 8.95 \) (correct to 2 d.p.).
A1: For \( x = 0.77 \) (correct to 2 d.p.).

(c) B1: For choosing \( x = 8.95 \) and giving the reason that \( x = 0.77 \) leads to a negative speed.
M1: For calculating \( \frac{15}{\text{their } x - 2} \).
A1: For 2 hours and 10 minutes.

(d) M1: For \( \frac{27}{3.5} \).
A1: For \( 7.71 \) (or \( 7.714 \)).
Question 3 · Structured Multi-Part
13 marks
(a) Simplify fully: \( \frac{2x^2 - 8}{x^2 + 5x - 14} \). [4]

(b) Express as a single fraction in its simplest form: \( \frac{3}{2x - 1} -
\frac{2}{x + 3} \). [4]

(c) Rearrange the formula \( y = \frac{3x - 5}{2x + 1} \) to make \( x \) the subject. [5]
Show answer & marking scheme

Worked solution

(a) Factor the numerator: \( 2x^2 - 8 = 2(x^2 - 4) = 2(x - 2)(x + 2) \).
Factor the denominator: \( x^2 + 5x - 14 = (x + 7)(x - 2) \).
Simplify by cancelling the common factor \( (x - 2) \):
\( \frac{2(x - 2)(x + 2)}{(x + 7)(x - 2)} = \frac{2(x + 2)}{x + 7} = \frac{2x + 4}{x + 7} \).

(b) Find a common denominator: \( (2x - 1)(x + 3) \).
Express with the common denominator:
\( \frac{3(x + 3) - 2(2x - 1)}{(2x - 1)(x + 3)} \)
Expand and simplify the numerator:
\( 3x + 9 - 4x + 2 = -x + 11 \).
So, the simplified fraction is \( \frac{11 - x}{(2x - 1)(x + 3)} \).

(c) Multiply both sides by \( (2x + 1) \):
\( y(2x + 1) = 3x - 5 \)
\( 2xy + y = 3x - 5 \)
Group terms containing \( x \) on one side:
\( y + 5 = 3x - 2xy \)
Factor out \( x \):
\( y + 5 = x(3 - 2y) \)
Divide by \( (3 - 2y) \):
\( x = \frac{y + 5}{3 - 2y} \).

Marking scheme

(a) M1: For factoring numerator: \( 2(x - 2)(x + 2) \).
M1: For factoring denominator: \( (x + 7)(x - 2) \).
M1: For cancelling common factor of \( (x - 2) \).
A1: For final answer \( \frac{2x + 4}{x + 7} \) (or \( \frac{2(x+2)}{x+7} \)).

(b) M1: For writing over a common denominator: \( (2x - 1)(x + 3) \).
M1: For expanding numerator: \( 3(x + 3) - 2(2x - 1) \).
A1: For correct expansion \( 3x + 9 - 4x + 2 \).
A1: For final answer \( \frac{11 - x}{(2x - 1)(x + 3)} \).

(c) M1: For multiplying by \( (2x + 1) \) correctly.
M1: For expanding to get \( 2xy + y = 3x - 5 \).
M1: For separating terms containing \( x \) on one side.
M1: For factoring out \( x \) from their terms.
A1: For final correct rearranged formula \( x = \frac{y + 5}{3 - 2y} \) (or equivalent).
Question 4 · Structured Multi-Part
13 marks
A solid toy consists of a cone of base radius \( 4 \) cm and height \( 6 \) cm fixed on top of a cylinder of radius \( 4 \) cm and height \( 10 \) cm.

(a) Calculate the total volume of the toy, giving your answer correct to 3 significant figures. [3]

(b) Calculate the slant height of the cone. [2]

(c) Calculate the total surface area of the toy (including the circular flat base at the bottom), giving your answer correct to 3 significant figures. [5]

(d) A mathematically similar toy has a volume of \( 2035 \) cm\(^3 \). Calculate the height of the cylinder of this larger toy, giving your answer correct to 3 significant figures. [3]
Show answer & marking scheme

Worked solution

(a) Volume of cylinder: \( V_{\text{cyl}} = \pi r^2 h = \pi \times 4^2 \times 10 = 160\pi \approx 502.65 \) cm\(^3 \).
Volume of cone: \( V_{\text{cone}} = \frac{1}{3}\pi r^2 H = \frac{1}{3} \times \pi \times 4^2 \times 6 = 32\pi \approx 100.53 \) cm\(^3 \).
Total volume: \( V_{\text{total}} = 160\pi + 32\pi = 192\pi \approx 603.19 \) cm\(^3 \).
To 3 s.f., the total volume is \( 603 \) cm\(^3 \).

(b) Using Pythagoras' theorem for the slant height, \( l \), of the cone:
\( l = \sqrt{r^2 + H^2} = \sqrt{4^2 + 6^2} = \sqrt{16 + 36} = \sqrt{52} \approx 7.211 \) cm.
To 3 s.f., the slant height is \( 7.21 \) cm.

(c) Total Surface Area comprises:
1. Base area of cylinder: \( \pi r^2 = \pi \times 4^2 = 16\pi \approx 50.27 \) cm\(^2 \).
2. Curved surface area of cylinder: \( 2\pi r h = 2\pi \times 4 \times 10 = 80\pi \approx 251.33 \) cm\(^2 \).
3. Curved surface area of cone: \( \pi r l = \pi \times 4 \times \sqrt{52} \approx 90.62 \) cm\(^2 \).
Total Surface Area:
\( A_{\text{total}} = 16\pi + 80\pi + 4\pi\sqrt{52} = 96\pi + 4\pi\sqrt{52} \approx 301.59 + 90.62 = 392.21 \) cm\(^2 \).
To 3 s.f., the total surface area is \( 392 \) cm\(^2 \).

(d) Let the linear scale factor be \( k \).
\( k^3 = \frac{V_{\text{large}}}{V_{\text{small}}} = \frac{2035}{192\pi} \approx \frac{2035}{603.186} \approx 3.3736 \).
\( k = \sqrt[3]{3.3736} \approx 1.4998 \).
Height of the cylinder of the larger toy:
\( h_{\text{large}} = 10 \times k \approx 10 \times 1.4998 = 14.998 \) cm.
To 3 s.f., the height of the cylinder is \( 15.0 \) cm.

Marking scheme

(a) M1: For correct volume of cylinder formula: \( \pi \times 4^2 \times 10 \).
M1: For correct volume of cone formula: \( \frac{1}{3} \times \pi \times 4^2 \times 6 \).
A1: For total volume \( 603 \) (or 603.1 - 603.2).

(b) M1: For \( \sqrt{4^2 + 6^2} \).
A1: For \( 7.21 \) (or 7.211).

(c) B1: For area of base \( 16\pi \) (or 50.3).
M1: For curved surface area of cylinder: \( 2\pi \times 4 \times 10 = 80\pi \) (or 251).
M1: For curved surface area of cone: \( \pi \times 4 \times \text{their } l \).
M1: For summing their three calculated areas.
A1: For total area \( 392 \) (or 392.2).

(d) M1: For setting up the ratio of volumes: \( \frac{2035}{603} \) (or \( \frac{2035}{192\pi} \)).
M1: For taking the cube root of the volume ratio to get linear scale factor \( k \).
A1: For \( 15.0 \) (accept 15).
Question 5 · Structured Multi-Part
13 marks
A bag contains 12 counters: 6 are red, 4 are blue, and 2 are green.
Two counters are drawn at random from the bag, one after another, without replacement.

(a) Find the probability that both counters are of the same color. [4]

(b) Find the probability that at least one of the counters drawn is red. [3]

(c) Given that the second counter drawn is blue, calculate the probability that the first counter drawn was red. [4]

(d) A third counter is now drawn from the remaining 10 counters. If the first two counters drawn were both red, calculate the probability that the third counter is also red. [2]
Show answer & marking scheme

Worked solution

(a) Total counters = 12.
Probability of both Red:
\( P(\text{Red}, \text{Red}) = \frac{6}{12} \times \frac{5}{11} = \frac{30}{132} \).
Probability of both Blue:
\( P(\text{Blue}, \text{Blue}) = \frac{4}{12} \times \frac{3}{11} = \frac{12}{132} \).
Probability of both Green:
\( P(\text{Green}, \text{Green}) = \frac{2}{12} \times \frac{1}{11} = \frac{2}{132} \).
Probability of same color:
\( P(\text{Same}) = \frac{30 + 12 + 2}{132} = \frac{44}{132} = \frac{1}{3} \approx 0.333 \).

(b) The complement event is "neither counter is red".
There are 6 counters that are not red (4 blue + 2 green).
\( P(\text{No Red}) = \frac{6}{12} \times \frac{5}{11} = \frac{30}{132} \).
\( P(\text{At least one Red}) = 1 - P(\text{No Red}) = 1 - \frac{30}{132} = \frac{102}{132} = \frac{17}{22} \approx 0.773 \).

(c) We want to find the conditional probability \( P(\text{First Red} \mid \text{Second Blue}) = \frac{P(\text{First Red and Second Blue})}{P(\text{Second Blue})} \).
\( P(\text{First Red and Second Blue}) = P(\text{Red}, \text{Blue}) = \frac{6}{12} \times \frac{4}{11} = \frac{24}{132} \).
To find \( P(\text{Second Blue}) \), we sum all possibilities where the second is blue:
\( P(\text{Second Blue}) = P(\text{Red}, \text{Blue}) + P(\text{Blue}, \text{Blue}) + P(\text{Green}, \text{Blue}) \)
\( P(\text{Second Blue}) = \frac{6}{12} \times \frac{4}{11} + \frac{4}{12} \times \frac{3}{11} + \frac{2}{12} \times \frac{4}{11} = \frac{24 + 12 + 8}{132} = \frac{44}{132} \).
Thus, the conditional probability is:
\( P(\text{First Red} \mid \text{Second Blue}) = \frac{24/132}{44/132} = \frac{24}{44} = \frac{6}{11} \approx 0.545 \).

(d) If the first two counters drawn were red, 4 red counters remain in the bag out of a total of 10 remaining counters.
\( P(\text{Third is Red}) = \frac{4}{10} = \frac{2}{5} = 0.4 \).

Marking scheme

(a) M1: For calculating any correct joint probability (e.g., Red/Red: \( \frac{30}{132} \)).
M1: For summing three correct same-color scenarios: \( P(\text{RR}) + P(\text{BB}) + P(\text{GG}) \).
A1: For unsimplified fraction \( \frac{44}{132} \) (or equivalent fraction).
A1: For final answer \( \frac{1}{3} \) (or 0.333).

(b) M1: For attempting to use the complement method or listing out options (RR, RB, RG, BR, GR).
M1: For correct probability \( \frac{30}{132} \) of getting no red counters.
A1: For \( \frac{17}{22} \) (or 0.773).

(c) M1: For finding \( P(\text{Red, Blue}) = \frac{24}{132} \).
M1: For identifying and summing the three paths for Second Blue: \( \frac{44}{132} \).
M1: For dividing \( \frac{P(\text{Red, Blue})}{P(\text{Second Blue})} \).
A1: For \( \frac{6}{11} \) (or 0.545).

(d) M1: For establishing remaining counters (4 red out of 10 total).
A1: For \( \frac{2}{5} \) (or 0.4).
Question 6 · Structured Multi-Part
13 marks
Consider the function \( g(x) = 3\sin(2x) - 1 \) for \( 0^\circ \le x \le 180^\circ \).

(a) Find the coordinates of the maximum and minimum points of the curve \( y = g(x) \) in the given range. [4]

(b) Solve the equation \( g(x) = 0 \) for \( 0^\circ \le x \le 180^\circ \), giving your answers correct to 1 decimal place. [5]

(c) Describe fully the three single transformations that map the graph of \( y = \sin(x) \) onto the graph of \( y = 3\sin(2x) - 1 \). [4]
Show answer & marking scheme

Worked solution

(a) The maximum value of \( \sin(2x) \) is \( 1 \).
This occurs when \( 2x = 90^\circ \implies x = 45^\circ \).
At \( x = 45^\circ \), \( y = 3(1) - 1 = 2 \).
So, the Maximum point is \( (45^\circ, 2) \).

The minimum value of \( \sin(2x) \) is \( -1 \).
This occurs when \( 2x = 270^\circ \implies x = 135^\circ \).
At \( x = 135^\circ \), \( y = 3(-1) - 1 = -4 \).
So, the Minimum point is \( (135^\circ, -4) \).

(b) Set \( 3\sin(2x) - 1 = 0 \implies \sin(2x) = \frac{1}{3} \).
Find the principal angle: \( 2x = \sin^{-1}\left(\frac{1}{3}\right) \approx 19.47^\circ \).
Since \( 0^\circ \le x \le 180^\circ \), the range for \( 2x \) is \( 0^\circ \le 2x \le 360^\circ \).
The values of \( 2x \) are:
\( 2x = 19.47^\circ \) and \( 2x = 180^\circ - 19.47^\circ = 160.53^\circ \).
Dividing by 2 gives:
\( x = 9.735^\circ \approx 9.7^\circ \)
\( x = 80.265^\circ \approx 80.3^\circ \).

(c) The three transformations are:
1. A stretch parallel to the \( y \)-axis (vertical stretch) with a scale factor of 3.
2. A stretch parallel to the \( x \)-axis (horizontal stretch) with a scale factor of \( 0.5 \) (or \( \frac{1}{2} \)).
3. A translation of 1 unit down, represented by the vector \( \begin{pmatrix} 0 \\ -1 \end{pmatrix} \).

Marking scheme

(a) B1: For finding \( y_{\text{max}} = 2 \) and \( y_{\text{min}} = -4 \).
M1: For setting \( 2x = 90 \) and \( 2x = 270 \) to find \( x \)-coordinates.
A1: For Max point \( (45, 2) \).
A1: For Min point \( (135, -4) \).

(b) M1: For \( \sin(2x) = \frac{1}{3} \).
M1: For finding the first angle \( 2x = 19.5 \) (or 19.47).
M1: For finding the second angle \( 2x = 160.5 \).
A1: For \( x = 9.7^\circ \).
A1: For \( x = 80.3^\circ \).

(c) B1: For vertical stretch, scale factor 3.
B1: For horizontal stretch, scale factor 0.5 (or \( \frac{1}{2} \)).
B2: For translation of \( \begin{pmatrix} 0 \\ -1 \end{pmatrix} \) (B1 for 'translation' and B1 for vector or '1 unit down').
Question 7 · Structured Multi-Part
13 marks
Three landmarks, \( A \), \( B \), and \( C \), are situated in a flat open plain.
\( B \) is \( 18 \) km from \( A \) on a bearing of \( 055^\circ \).
\( C \) is \( 25 \) km from \( A \) on a bearing of \( 130^\circ \).

(a) Calculate the distance \( BC \), giving your answer in km correct to 3 significant figures. [4]

(b) Calculate the bearing of \( C \) from \( B \), giving your answer correct to 1 decimal place. [5]

(c) Calculate the area of triangle \( ABC \), giving your answer in km\(^2 \) correct to 3 significant figures. [2]

(d) Calculate the shortest distance from landmark \( A \) to the path directly connecting \( B \) and \( C \). [2]
Show answer & marking scheme

Worked solution

(a) The angle \( \angle BAC \) is the difference in bearings:
\( \angle BAC = 130^\circ - 55^\circ = 75^\circ \).
We use the Cosine Rule to find \( BC \):
\( BC^2 = AB^2 + AC^2 - 2(AB)(AC)\cos(\angle BAC) \)
\( BC^2 = 18^2 + 25^2 - 2(18)(25)\cos(75^\circ) \)
\( BC^2 = 324 + 625 - 900\cos(75^\circ) \)
\( BC^2 = 949 - 900(0.258819) = 949 - 232.937 = 716.063 \).
\( BC = \sqrt{716.063} \approx 26.759 \) km.
To 3 s.f., the distance is \( 26.8 \) km.

(b) First, use the Sine Rule to find the angle \( \angle ABC \):
\( \frac{\sin(\angle ABC)}{AC} = \frac{\sin(\angle BAC)}{BC} \)
\( \sin(\angle ABC) = \frac{25 \times \sin(75^\circ)}{26.759} \approx \frac{24.148}{26.759} \approx 0.90242 \).
\( \angle ABC = \sin^{-1}(0.90242) \approx 64.48^\circ \).
Now find the bearing. Draw a North line at \( B \).
Since the bearing of \( B \) from \( A \) is \( 055^\circ \), the line \( BA \) has a back-bearing of \( 55^\circ + 180^\circ = 235^\circ \).
Because \( C \) is further south-east, looking from \( B \) to \( A \) (direction \( 235^\circ \)), we turn counter-clockwise by angle \( \angle ABC \) to look towards \( C \).
So, the bearing of \( C \) from \( B \) is:
\( 235^\circ - 64.48^\circ = 170.52^\circ \approx 170.5^\circ \).

(c) Area of triangle \( ABC \):
\( \text{Area} = \frac{1}{2} \times AB \times AC \times \sin(\angle BAC) \)
\( \text{Area} = \frac{1}{2} \times 18 \times 25 \times \sin(75^\circ) = 225 \times 0.96593 \approx 217.33 \) km\(^2 \).
To 3 s.f., the area is \( 217 \) km\(^2 \).

(d) The shortest distance \( d \) from \( A \) to \( BC \) is the perpendicular height of triangle \( ABC \) when \( BC \) is the base:
\( \text{Area} = \frac{1}{2} \times BC \times d \)
\( 217.33 = \frac{1}{2} \times 26.759 \times d \)
\( d = \frac{2 \times 217.33}{26.759} \approx 16.24 \) km.
To 3 s.f., the shortest distance is \( 16.2 \) km.

Marking scheme

(a) B1: For \( \angle BAC = 75^\circ \).
M1: For substituting into Cosine Rule correctly.
A1: For \( BC^2 = 716.06 \).
A1: For \( BC = 26.8 \) km (accept 26.75-26.8).

(b) M1: For substituting into Sine Rule correctly.
A1: For \( \sin(\angle ABC) \approx 0.902 \).
A1: For \( \angle ABC = 64.5^\circ \) (or 64.48).
M1: For correct bearing calculation step: \( 235 - \text{their } 64.5 \).
A1: For bearing \( 170.5^\circ \).

(c) M1: For correct area formula: \( \frac{1}{2} \times 18 \times 25 \times \sin(75^\circ) \).
A1: For \( 217 \) km\(^2 \) (or 217.3).

(d) M1: For setting up equation \( \frac{1}{2} \times BC \times d = \text{Area} \).
A1: For \( 16.2 \) km (or 16.24).
Question 8 · Structured Multi-Part
13 marks
Solve the simultaneous equations:

\[ 2x + y = 7 \]
\[ 3x^2 - y^2 = 8 \]

(a) Show that substituting \( y = 7 - 2x \) into the second equation yields the quadratic equation \( x^2 - 28x + 57 = 0 \). [4]

(b) Solve the equation \( x^2 - 28x + 57 = 0 \), giving your answers correct to 3 significant figures. [5]

(c) Find the corresponding values of \( y \), and state your final solutions as coordinate pairs \( (x, y) \). [4]
Show answer & marking scheme

Worked solution

(a) Express \( y \) in terms of \( x \) from the first equation:
\( y = 7 - 2x \).
Substitute this into the second equation:
\( 3x^2 - (7 - 2x)^2 = 8 \)
Expand the squared term:
\( (7 - 2x)^2 = 49 - 28x + 4x^2 \).
Now substitute this expansion back into the equation:
\( 3x^2 - (49 - 28x + 4x^2) = 8 \)
Remove parentheses by distributing the negative sign:
\( 3x^2 - 49 + 28x - 4x^2 = 8 \)
Simplify terms:
\( -x^2 + 28x - 49 = 8 \)
Move all terms to one side to set to zero:
\( -x^2 + 28x - 57 = 0 \)
Multiply by \(-1\) to get the required form:
\( x^2 - 28x + 57 = 0 \) (Showed)

(b) Using the quadratic formula:
\( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \)
\( x = \frac{28 \pm \sqrt{(-28)^2 - 4(1)(57)}}{2} \)
\( x = \frac{28 \pm \sqrt{784 - 228}}{2} = \frac{28 \pm \sqrt{556}}{2} \)
\( \sqrt{556} \approx 23.5796 \)
\( x_1 = \frac{28 + 23.5796}{2} \approx 25.7898 \implies 25.8 \) (to 3 s.f.)
\( x_2 = \frac{28 - 23.5796}{2} \approx 2.2102 \implies 2.21 \) (to 3 s.f.)

(c) Substitute the \( x \) values back into \( y = 7 - 2x \):
For \( x_1 = 25.7898 \):
\( y_1 = 7 - 2(25.7898) = 7 - 51.5796 = -44.5796 \approx -44.6 \).
For \( x_2 = 2.2102 \):
\( y_2 = 7 - 2(2.2102) = 7 - 4.4204 = 2.5796 \approx 2.58 \).
So the solutions are \( (25.8, -44.6) \) and \( (2.21, 2.58) \).

Marking scheme

(a) M1: For writing \( y = 7 - 2x \) or equivalent expression.
M1: For substitution of their expression into \( 3x^2 - y^2 = 8 \).
A1: For expanding \( (7-2x)^2 \) correctly as \( 49 - 28x + 4x^2 \).
A1: For simplifying to the target equation \( x^2 - 28x + 57 = 0 \) with all steps shown.

(b) M1: For correct substitution into the quadratic formula.
A1: For \( \sqrt{556} \) or \( 23.579... \).
A1: For \( x = 25.8 \).
A1: For \( x = 2.21 \).
B1: For answers rounded to 3 significant figures.

(c) M1: For attempting to substitute at least one of their \( x \) values into a linear equation to find \( y \).
A1: For \( y_1 \approx -44.6 \).
A1: For \( y_2 \approx 2.58 \).
A1: For writing final answers as coordinate pairs: \( (25.8, -44.6) \) and \( (2.21, 2.58) \).
Question 9 · Structured Multi-Part
13 marks
A cyclist travels 36 km on an outward journey at an average speed of \(x\) km/h.

(a) Write down an expression, in terms of \(x\), for the time taken, in hours, for:
(i) the outward journey,
(ii) the return journey, where the average speed was 3 km/h slower.

(b) The return journey took 40 minutes longer than the outward journey. Write down an equation in \(x\) and show that it simplifies to \(x^2 - 3x - 162 = 0\).

(c) Solve the equation \(x^2 - 3x - 162 = 0\) to find the speed of the outward journey. Show all your working.

(d) Bilal also travels 36 km. His average speed is such that the journey takes \(t\) hours. If his average speed had been 2 km/h faster, the journey would have taken 1.5 hours less.
Form an equation in \(t\), show that it simplifies to \(2t^2 - 3t - 54 = 0\), and solve it to find the value of \(t\).
Show answer & marking scheme

Worked solution

Let's solve each part systematically:

(a)(i) Speed is given by \(v = \frac{d}{t}\), so time is \(t = \frac{d}{v}\).
For the outward journey, distance is 36 km and average speed is \(x\) km/h.
Time taken = \(\frac{36}{x}\) hours.

(a)(ii) On the return journey, the speed is 3 km/h slower, so speed = \(x - 3\) km/h.
Time taken = \(\frac{36}{x - 3}\) hours.

(b) The return journey takes 40 minutes longer than the outward journey.
Since 40 minutes = \(\frac{40}{60} = \frac{2}{3}\) hours:
\(\frac{36}{x - 3} - \frac{36}{x} = \frac{2}{3}\)

Divide the entire equation by 2:
\(\frac{18}{x - 3} - \frac{18}{x} = \frac{1}{3}\)

Multiply through by the common denominator \(3x(x - 3)\):
\(3x(18) - 3(x - 3)(18) = x(x - 3)\)
\(54x - 54(x - 3) = x^2 - 3x\)
\(54x - 54x + 162 = x^2 - 3x\)
\(162 = x^2 - 3x\)
\(x^2 - 3x - 162 = 0\) (as required).

(c) Solve \(x^2 - 3x - 162 = 0\):
Factorising the quadratic equation:
\((x - 18)(x + 9) = 0\)
This gives \(x = 18\) or \(x = -9\).
Since speed must be positive, the speed of the outward journey is \(18\) km/h.

(d) For Bilal:
Original speed = \(\frac{36}{t}\) km/h.
If his speed is 2 km/h faster, his new speed is \(\frac{36}{t} + 2\) km/h.
His new time is \(t - 1.5\) hours.
Since distance = speed \(\times\) time:
\(\left(\frac{36}{t} + 2\right)(t - 1.5) = 36\)

Expand the brackets:
\(36 - \frac{54}{t} + 2t - 3 = 36\)
\(2t - 3 - \frac{54}{t} = 0\)

Multiply by \(t\):
\(2t^2 - 3t - 54 = 0\) (as required).

Solve \(2t^2 - 3t - 54 = 0\) by factorising:
\((2t + 9)(t - 6) = 0\)
This gives \(t = 6\) or \(t = -4.5\).
Since time must be positive, \(t = 6\).

Marking scheme

(a)(i) [1 mark] B1 for \(\frac{36}{x}\)
(a)(ii) [1 mark] B1 for \(\frac{36}{x - 3}\)
(b) [4 marks] M1 for setting up algebraic equation \(\frac{36}{x - 3} - \frac{36}{x} = \frac{40}{60}\) (or equivalent)
M1 for eliminating denominators, e.g., \(36x - 36(x-3) = \frac{2}{3}x(x-3)\)
M1 for expanding brackets: \(36x - 36x + 108 = \frac{2}{3}x^2 - 2x\)
A1 for fully correct simplification leading to \(x^2 - 3x - 162 = 0\) with no errors seen.
(c) [3 marks] M1 for factorising \((x - 18)(x + 9)\) or correct substitution into quadratic formula.
A1 for \(x = 18\) and \(x = -9\) as algebraic solutions.
A1 for selecting positive value \(18\) as final answer.
(d) [4 marks] M1 for expression of new speed \(\frac{36}{t} + 2\) or new time \(t - 1.5\).
M1 for setting up the equation \((\frac{36}{t} + 2)(t - 1.5) = 36\) or equivalent.
M1 for simplifying to \(2t^2 - 3t - 54 = 0\) and attempting to solve (by factorising or formula).
A1 for \(t = 6\) (rejecting \(-4.5\)).
Question 10 · Structured Multi-Part
13 marks
Consider the function \(f(x) = x^2 - \frac{4}{x}\) for \(0.5 \le x \le 4\).

(a) Complete the table of values for \(y = x^2 - \frac{4}{x}\).
\begin{array}{|c|c|c|c|c|c|c|c|}
\hline
x & 0.5 & 1 & 1.5 & 2 & 2.5 & 3 & 4 \\
\hline
y & -7.75 & p & -0.42 & q & 4.65 & r & 15 \\
\hline
\end{array}

(b) Find the \(x\)-coordinate of the point where the curve crosses the \(x\)-axis. Give your answer correct to 3 significant figures.

(c) Find the derivative \(\frac{dy}{dx}\).

(d) Use your answer to part (c) to find the gradient of the curve at the point where \(x = 2\).

(e) Find the equation of the tangent to the curve at the point where \(x = 2\). Give your answer in the form \(y = mx + c\).
Show answer & marking scheme

Worked solution

(a) Let us calculate the missing values in the table:
When \(x = 1\):
\(y = 1^2 - \frac{4}{1} = 1 - 4 = -3\).
So, \(p = -3\).

When \(x = 2\):
\(y = 2^2 - \frac{4}{2} = 4 - 2 = 2\).
So, \(q = 2\).

When \(x = 3\):
\(y = 3^2 - \frac{4}{3} = 9 - 1.333... = 7.67\) (to 3 s.f.).
So, \(r = 7.67\).

(b) The curve crosses the \(x\)-axis when \(y = 0\):
\(x^2 - \frac{4}{x} = 0\)
\(x^2 = \frac{4}{x}\)
\(x^3 = 4\)
\(x = \sqrt[3]{4} \approx 1.5874...\)
To 3 significant figures, \(x = 1.59\).

(c) Rewrite \(y\) as \(y = x^2 - 4x^{-1}\).
Differentiating with respect to \(x\):
\(\frac{dy}{dx} = 2x - 4(-1)x^{-2} = 2x + 4x^{-2} = 2x + \frac{4}{x^2}\).

(d) To find the gradient of the curve at \(x = 2\), substitute \(x = 2\) into the derivative:
\(\text{Gradient} = 2(2) + \frac{4}{2^2} = 4 + \frac{4}{4} = 4 + 1 = 5\).

(e) The tangent is a straight line \(y = mx + c\) with gradient \(m = 5\).
The point of tangency is \((2, 2)\) since \(x = 2\) and \(y = 2\).
Substitute \((2, 2)\) and \(m = 5\) into \(y - y_1 = m(x - x_1)\):
\(y - 2 = 5(x - 2)\)
\(y - 2 = 5x - 10\)
\(y = 5x - 8\).

Marking scheme

(a) [3 marks] B1 for \(p = -3\).
B1 for \(q = 2\).
B1 for \(r = 7.67\) (or \(7.7\) or \(7\frac{2}{3}\)).

(b) [2 marks] M1 for setting \(x^2 - \frac{4}{x} = 0\) and obtaining \(x^3 = 4\).
A1 for \(1.59\) (or \(1.587...\)).

(c) [2 marks] M1 for \(2x\) or \(4/x^2\) (or \(4x^{-2}\)).
A1 for fully correct derivative: \(2x + \frac{4}{x^2}\).

(d) [2 marks] M1 for substituting \(x = 2\) into their derivative.
A1 for gradient = \(5\).

(e) [4 marks] M1 for using their gradient (5) as \(m\) in \(y = mx + c\).
M1 for finding the point coordinates \((2, 2)\) by using \(x=2\) in the original function.
M1 for substituting \((2, 2)\) and \(m=5\) into \(y - y_1 = m(x - x_1)\) or equivalent.
A1 for \(y = 5x - 8\).

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