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AQA Level 2 Certificate Further Mathematics Paper 1 (Non-Calculator)
๐ก How to use this page
- Attempt First: Try solving the problem yourself before checking the solution.
- Active Learning: The “Why” sections explain the strategy, while “Working” shows the math.
- No Calculator: This is a non-calculator paper. All arithmetic methods are shown fully.
Table of Contents
- Question 1 (Indices)
- Question 2 (Surds & Equations)
- Question 3 (Algebraic Identities)
- Question 4 (Coordinate Geometry)
- Question 5 (Differentiation)
- Question 6 (Algebraic Fractions)
- Question 7 (Area of Rhombus)
- Question 8 (Curve Sketching)
- Question 9 (Circle Theorems)
- Question 10 (Composite Functions)
- Question 11 (Circle Equation)
- Question 12 (Cosine Rule)
- Question 13 (Rearranging Formulae)
- Question 14 (Surds)
- Question 15 (Normals & Intersection)
- Question 16 (Binomial Expansion)
- Question 17 (Simultaneous Equations)
- Question 18 (Fractional Indices)
- Question 19 (Increasing Functions)
- Question 20 (Trigonometric Equations)
Question 1 (4 marks total)
1(a) \( \frac{y^6 \times y}{y^m} = y^4 \)
Circle the value of \( m \).
[ -2 ] [ 1.5 ] [ 2 ] [ 3 ]
1(b) \( a^n \times a^5 = a^5 \)
Work out the value of \( n \).
1(c) \( (c^{5p}) = (c^2)^6 \)
Work out the value of \( p \).
Worked Solution
Part 1(a): Finding m
๐ก Strategy: Use the laws of indices. Multiplication adds powers, division subtracts powers.
โ Working:
First, simplify the numerator:
\[ y^6 \times y^1 = y^{6+1} = y^7 \]Now substitute this back into the fraction:
\[ \frac{y^7}{y^m} = y^4 \]Using the division law (subtract powers):
\[ 7 – m = 4 \] \[ 7 – 4 = m \] \[ m = 3 \]Answer: Circle 3
โ (1 mark)
Part 1(b): Finding n
๐ก Strategy: Use the multiplication law of indices: \( a^x \times a^y = a^{x+y} \).
โ Working:
\[ a^n \times a^5 = a^{n+5} \]We are told this equals \( a^5 \), so:
\[ n + 5 = 5 \] \[ n = 0 \]Answer: \( n = 0 \)
โ (1 mark)
Part 1(c): Finding p
๐ก Strategy: Use the power law of indices: \( (a^x)^y = a^{xy} \). Make the powers equal.
โ Working:
Left Hand Side (LHS) is already simplified: \( c^{5p} \)
Right Hand Side (RHS):
\[ (c^2)^6 = c^{2 \times 6} = c^{12} \]Equate the powers:
\[ 5p = 12 \] \[ p = \frac{12}{5} \]To convert to a decimal, multiply numerator and denominator by 2:
\[ p = \frac{24}{10} = 2.4 \]Final Answer: \( p = 2.4 \) (or \( \frac{12}{5} \))
โ (2 marks)
Question 2 (2 marks)
Solve \( \sqrt[3]{7x – 13} = 2 \)
Worked Solution
Step 1: Eliminate the cube root
๐ก Strategy: To remove a cube root, we must cube both sides of the equation.
โ Working:
\[ (\sqrt[3]{7x – 13})^3 = 2^3 \] \[ 7x – 13 = 8 \]โ (M1) Attempt to cube both sides
Step 2: Solve for x
๐ก Strategy: Isolate \( x \) by adding 13 to both sides and then dividing by 7.
โ Working:
\[ 7x = 8 + 13 \] \[ 7x = 21 \] \[ x = \frac{21}{7} \] \[ x = 3 \]Final Answer: \( x = 3 \)
โ (Total: 2 marks)
Question 3 (4 marks)
\( 3a(2x – 1) + 4(ax + 5) \equiv 60x + b \)
Work out the values of \( a \) and \( b \).
Worked Solution
Step 1: Expand the brackets on the LHS
๐ก Strategy: To compare coefficients, we first need to expand the left-hand side (LHS) to look like the right-hand side (RHS).
โ Working:
\[ 3a(2x) – 3a(1) + 4(ax) + 4(5) \] \[ 6ax – 3a + 4ax + 20 \]โ (M1) Both brackets expanded correctly
Step 2: Collect like terms
๐ก Strategy: Group the \( x \) terms together and the constant terms (those without \( x \)) together.
โ Working:
\( x \) terms: \( 6ax + 4ax = 10ax \)
Constant terms: \( -3a + 20 \)
So the LHS becomes:
\[ 10ax + (20 – 3a) \]Step 3: Compare coefficients
๐ก Strategy: The identity symbol (\(\equiv\)) means the coefficient of \( x \) on the LHS must equal the coefficient of \( x \) on the RHS, and the constants must also match.
LHS: \( (10a)x + (20 – 3a) \)
RHS: \( 60x + b \)
โ Working:
Compare x terms:
\[ 10a = 60 \] \[ a = \frac{60}{10} \] \[ a = 6 \]โ (A1) Value of a correct
Compare constants:
\[ 20 – 3a = b \]Substitute \( a = 6 \):
\[ 20 – 3(6) = b \] \[ 20 – 18 = b \] \[ b = 2 \]โ (A1) Value of b correct
Final Answer: \( a = 6, \quad b = 2 \)
โ (Total: 4 marks)
Question 4 (4 marks)
\( ABC \) is a straight line with \( AB : BC = 5 : 2 \).
Work out the coordinates of \( C \).
Worked Solution
Step 1: Calculate the change from A to B
๐ก Strategy: Finding the difference in x and y coordinates between A and B tells us the vector for “5 parts” of the journey.
\( A = (3, 7) \)
\( B = (5, 5.5) \)
โ Working:
Change in x: \( 5 – 3 = 2 \)
Change in y: \( 5.5 – 7 = -1.5 \)
So, the vector \( \vec{AB} = \begin{pmatrix} 2 \\ -1.5 \end{pmatrix} \).
Step 2: Find the value of 1 part
๐ก Strategy: Since the ratio \( AB : BC \) is \( 5 : 2 \), the vector \( \vec{AB} \) represents 5 parts. Divide by 5 to find the vector for 1 part.
โ Working:
1 part x-change: \( \frac{2}{5} = 0.4 \)
1 part y-change: \( \frac{-1.5}{5} = -0.3 \)
โ (M1) Method to find unit change
Step 3: Calculate the change from B to C
๐ก Strategy: The distance from B to C is “2 parts”. Multiply the single part vector by 2.
โ Working:
Change in x (2 parts): \( 0.4 \times 2 = 0.8 \)
Change in y (2 parts): \( -0.3 \times 2 = -0.6 \)
โ (M1) Method to find vector BC
Step 4: Apply to B to find C
๐ก Strategy: Add the change from B to C to the coordinates of B.
โ Working:
\( x_C = x_B + 0.8 = 5 + 0.8 = 5.8 \)
\( y_C = y_B – 0.6 = 5.5 – 0.6 = 4.9 \)
Final Answer: \( (5.8, 4.9) \)
โ (Total: 4 marks)
Question 5 (3 marks)
\( y = 2x^{10} – \frac{3}{x^2} \)
Work out \( \frac{dy}{dx} \).
Worked Solution
Step 1: Rewrite using indices
๐ก Strategy: Before differentiating, we must write all terms in the form \( ax^n \). The term \( \frac{3}{x^2} \) needs to be rewritten with a negative power.
โ Working:
\[ y = 2x^{10} – 3x^{-2} \]โ (M1) Correct index notation
Step 2: Differentiate
๐ก Strategy: Apply the power rule: multiply by the power, then subtract 1 from the power (\( nx^{n-1} \)).
โ Working:
Term 1: \( 2x^{10} \rightarrow 10 \times 2 x^{10-1} = 20x^9 \)
Term 2: \( -3x^{-2} \rightarrow -2 \times -3 x^{-2-1} = +6x^{-3} \)
โ (M1) Correct differentiation of at least one term
Final Answer: \( \frac{dy}{dx} = 20x^9 + 6x^{-3} \)
(Alternatively: \( 20x^9 + \frac{6}{x^3} \))
โ (Total: 3 marks)
Question 6 (3 marks)
Simplify fully:
\[ \frac{15x^2y – 5xy^2}{12x – 4y} \]Worked Solution
Step 1: Factorise the Numerator
๐ก Strategy: Look for the highest common factor in \( 15x^2y – 5xy^2 \). Both terms share \( 5 \), \( x \), and \( y \).
โ Working:
\[ 15x^2y – 5xy^2 = 5xy(3x – y) \]โ (M1) Numerator factorised correctly
Step 2: Factorise the Denominator
๐ก Strategy: Look for the highest common factor in \( 12x – 4y \). Both terms are divisible by 4.
โ Working:
\[ 12x – 4y = 4(3x – y) \]โ (M1) Denominator factorised correctly
Step 3: Cancel common terms
๐ก Strategy: Notice that \( (3x – y) \) appears in both the numerator and denominator. We can cancel it out.
โ Working:
\[ \require{cancel} \frac{5xy \cancel{(3x – y)}}{4 \cancel{(3x – y)}} \] \[ = \frac{5xy}{4} \]Final Answer: \( \frac{5xy}{4} \)
โ (Total: 3 marks)
Question 7 (3 marks)
\( ABCD \) is a rhombus with side length 8 cm.
Angle \( ABC = 60^\circ \).
Work out the area of the rhombus.
Give your answer in the form \( a\sqrt{b} \) cm\(^2\) where \( a \) and \( b \) are integers.
Worked Solution
Step 1: Understand the Geometry
๐ก Strategy: A rhombus can be split into two identical triangles (ABC and ADC). The area of a triangle is \( \frac{1}{2}ab\sin C \).
Step 2: Calculate Area of Triangle ABC
๐ก Strategy: We know sides \( AB = BC = 8 \) cm and angle \( B = 60^\circ \).
โ Working:
\[ \text{Area} = \frac{1}{2} \times 8 \times 8 \times \sin(60^\circ) \]We know that \( \sin(60^\circ) = \frac{\sqrt{3}}{2} \):
\[ \text{Area} = \frac{1}{2} \times 64 \times \frac{\sqrt{3}}{2} \] \[ \text{Area} = 32 \times \frac{\sqrt{3}}{2} = 16\sqrt{3} \]โ (M1) Correct method for area of triangle
Step 3: Total Area
๐ก Strategy: Multiply by 2 for the full rhombus.
โ Working:
\[ \text{Total Area} = 2 \times 16\sqrt{3} \] \[ = 32\sqrt{3} \]Final Answer: \( 32\sqrt{3} \) cm\(^2\)
โ (Total: 3 marks)
Question 8 (3 marks)
The curve \( y = 2x^3 – 3x^2 – 12x + 6 \)
- has a maximum point at \( L(-1, 13) \)
- has a minimum point at \( M(2, -14) \)
- intersects the y-axis at \( N \)
The curve crosses the x-axis at three distinct points.
On the axes below, sketch the curve.
Label the points \( L \), \( M \) and \( N \) on your sketch.
Worked Solution
Step 1: Identify Key Features
๐ก Strategy: A cubic graph with a positive \( x^3 \) coefficient starts from bottom-left and goes to top-right. We need to plot the specific points given.
- Maximum \( L(-1, 13) \): In the second quadrant (top-left).
- Minimum \( M(2, -14) \): In the fourth quadrant (bottom-right).
- Y-intercept \( N \): When \( x=0, y=6 \). Point is \( (0, 6) \).
Step 2: Sketching
๐ก Strategy: Draw a smooth ‘S’ shape curve.
- Start low on the left.
- Go up to cross the x-axis, reach peak at \( L \).
- Come down to cross the y-axis at \( N(0,6) \).
- Continue down to cross x-axis again, reach trough at \( M \).
- Go up to cross x-axis a third time.
Result: See diagram above. Correct shape with 3 x-intercepts and points L, M, N labeled correctly.
โ (3 marks)
Question 9 (4 marks)
\( A, B, C \) and \( D \) are points on a circle.
- \( \angle BCA = x \)
- \( \angle ACD = 2x \)
- \( \angle CAD = 3x \)
- \( \angle CAB = 4x \)
Prove that \( AC \) is a diameter.
Worked Solution
Step 1: Use Cyclic Quadrilateral Properties
๐ก Strategy: Opposite angles in a cyclic quadrilateral sum to \( 180^\circ \). Let’s look at angles at C and A.
โ Working:
Angle at \( C = \angle BCA + \angle ACD = x + 2x = 3x \)
Angle at \( A = \angle CAB + \angle CAD = 4x + 3x = 7x \)
Sum of opposite angles:
\[ 3x + 7x = 180^\circ \] \[ 10x = 180^\circ \] \[ x = 18^\circ \]โ (M1) Setting up equation for x
Step 2: Calculate Angle ADC
๐ก Strategy: To prove \( AC \) is a diameter, we need to show that the angle subtended by it at the circumference (Angle \( ADC \) or \( ABC \)) is \( 90^\circ \) (angle in a semicircle).
Let’s use triangle \( ADC \).
โ Working:
In \( \triangle ADC \):
- \( \angle CAD = 3x = 3(18) = 54^\circ \)
- \( \angle ACD = 2x = 2(18) = 36^\circ \)
Angles in a triangle sum to \( 180^\circ \):
\[ \angle ADC = 180 – (54 + 36) \] \[ \angle ADC = 180 – 90 \] \[ \angle ADC = 90^\circ \]โ (M1) Finding angle ADC is 90
Step 3: Conclusion
๐ก Strategy: State the circle theorem.
Since \( \angle ADC = 90^\circ \), the converse of the “angle in a semicircle” theorem states that the line subtending the \( 90^\circ \) angle at the circumference must be a diameter.
Therefore, AC is a diameter.
โ (Total: 4 marks)
Question 10 (5 marks)
\( f(x) = (\frac{9x}{2})^{-1} \)
\( g(x) = \sqrt[3]{1 – px} \)
Given that \( f(\frac{1}{3}) = g(\frac{1}{3}) \), work out the value of \( p \).
Worked Solution
Step 1: Simplify and Evaluate f(1/3)
๐ก Strategy: First, rewrite \( f(x) \) in a simpler form, then substitute \( x = 1/3 \).
โ Working:
\[ f(x) = \left( \frac{9x}{2} \right)^{-1} = \frac{2}{9x} \]Substitute \( x = \frac{1}{3} \):
\[ f(\frac{1}{3}) = \frac{2}{9(\frac{1}{3})} \] \[ = \frac{2}{3} \]Step 2: Evaluate g(1/3)
โ Working:
Note: The question text displayed \( g(x) = \sqrt[3]{1-px} \) in the prompt but let’s re-read the PDF snippet to be sure. Snippet says \( g(x) = \sqrt{1 – px^3} \) is incorrect, PDF says \( \sqrt[3]{1 – px} \) … wait, looking at PDF image… Page 10 of PDF.
Text says: \( g(x) = \sqrt[3]{1 – px^3} \)
Wait, re-reading OCR of page 10: “g(x) = \sqrt[3]{1 – px^3}”. Yes, there is a power of 3 on the x.
Substitute \( x = \frac{1}{3} \):
\[ g(\frac{1}{3}) = \sqrt[3]{1 – p(\frac{1}{3})^3} \] \[ = \sqrt[3]{1 – \frac{p}{27}} \]Step 3: Equate and Solve
๐ก Strategy: Set \( f(1/3) = g(1/3) \) and solve for \( p \).
โ Working:
\[ \frac{2}{3} = \sqrt[3]{1 – \frac{p}{27}} \]Cube both sides to remove the cube root:
\[ \left(\frac{2}{3}\right)^3 = 1 – \frac{p}{27} \] \[ \frac{8}{27} = 1 – \frac{p}{27} \]Multiply everything by 27 to clear denominators:
\[ 8 = 27 – p \] \[ p = 27 – 8 \] \[ p = 19 \]Correction: Let me re-read the question image carefully. The OCR said “sqrt 1 – px^3” with a 3 index? No, OCR says “g(x) = \sqrt{1 – px^3}”. Wait, let’s check the mark scheme.
Mark Scheme Q10 (Page 9 of MS PDF):
\( \frac{9}{2} \times \frac{1}{3} \) or \( \frac{3}{2} \) … wait, the MS has \( \frac{2}{3} \) squared? Ah, looking at MS:
“their \( \frac{2}{3} = \sqrt{1 – p \times (\frac{1}{3})^3} \)”
Then “their \( (\frac{2}{3})^2 = 1 – p \times … \)”
So it is a square root, not a cube root. And it is \( x^3 \).
Let’s Recalculate based on Square Root:
LHS = \( 2/3 \).
RHS = \( \sqrt{1 – p/27} \).
Square both sides: \( 4/9 = 1 – p/27 \).
Multiply by 27: \( 12 = 27 – p \).
\( p = 15 \).
Mark scheme answer is 15. So it is a Square Root.
Final Answer: \( p = 15 \)
โ (Total: 5 marks)
Question 11 (3 marks)
A circle, centre \( C \), touches the \( y \)-axis at the point \( (0, 2) \).
The line \( y = k \) intersects the circle at the points \( (1, k) \) and \( (5, k) \).
Work out the equation of the circle.
Worked Solution
Step 1: Find the y-coordinate of the centre
๐ก Strategy: The circle touches the y-axis at \( (0, 2) \). This means the tangent at that point is the y-axis (vertical). The radius is perpendicular to the tangent, so the radius to this point is horizontal.
Therefore, the centre of the circle must be directly to the right of \( (0, 2) \). This means the y-coordinate of the centre is 2.
Step 2: Find the x-coordinate of the centre
๐ก Strategy: The horizontal line \( y = k \) intersects the circle at \( x = 1 \) and \( x = 5 \). A perpendicular bisector from the centre splits a chord in half.
โ Working:
Since the points \( (1, k) \) and \( (5, k) \) are symmetric on the circle, the x-coordinate of the centre lies exactly halfway between them.
\[ x_{\text{centre}} = \frac{1 + 5}{2} = 3 \]So, the Centre \( C \) is at \( (3, 2) \).
Step 3: Determine the Radius and Equation
๐ก Strategy: The distance from the centre \( (3, 2) \) to the touching point on the y-axis \( (0, 2) \) is the radius.
โ Working:
\[ \text{Radius} = 3 – 0 = 3 \]The equation of a circle is \( (x – a)^2 + (y – b)^2 = r^2 \).
\[ (x – 3)^2 + (y – 2)^2 = 3^2 \] \[ (x – 3)^2 + (y – 2)^2 = 9 \]Final Answer: \( (x – 3)^2 + (y – 2)^2 = 9 \)
โ (Total: 3 marks)
Question 12 (3 marks)
\( AB = 4 \) cm, \( AC = 7 \) cm, \( \cos x = -\frac{2}{7} \).
Work out the length of \( BC \).
Worked Solution
Step 1: Identify the Rule
๐ก Strategy: We have two sides and the included angle (cosine given). This requires the Cosine Rule.
\( a^2 = b^2 + c^2 – 2bc \cos A \)
Step 2: Substitute and Solve
โ Working:
\[ BC^2 = 4^2 + 7^2 – 2(4)(7)\left(-\frac{2}{7}\right) \]Calculate squares:
\[ BC^2 = 16 + 49 – 56\left(-\frac{2}{7}\right) \]Simplify the multiplication (7 divides 56 to give 8):
\[ BC^2 = 65 – 8(-2) \] \[ BC^2 = 65 + 16 \] \[ BC^2 = 81 \]Square root for length:
\[ BC = \sqrt{81} = 9 \]Final Answer: \( 9 \) cm
โ (Total: 3 marks)
Question 13 (5 marks)
Rearrange \( t = \frac{3w^3 + a}{w^3 – 2} \) to make \( w \) the subject.
Worked Solution
Step 1: Clear the fraction
๐ก Strategy: Multiply both sides by the denominator \( (w^3 – 2) \).
โ Working:
\[ t(w^3 – 2) = 3w^3 + a \] \[ tw^3 – 2t = 3w^3 + a \]Step 2: Group w terms
๐ก Strategy: Move all terms containing \( w^3 \) to one side and everything else to the other.
โ Working:
\[ tw^3 – 3w^3 = a + 2t \]Step 3: Factorise and Isolate
๐ก Strategy: Factor out \( w^3 \) and then divide.
โ Working:
\[ w^3(t – 3) = a + 2t \] \[ w^3 = \frac{a + 2t}{t – 3} \]Step 4: Cube Root
โ Working:
\[ w = \sqrt[3]{\frac{a + 2t}{t – 3}} \]Final Answer: \( w = \sqrt[3]{\frac{a + 2t}{t – 3}} \)
โ (Total: 5 marks)
Question 14 (4 marks)
Rationalise and simplify \( \frac{\sqrt{3} – 7}{\sqrt{3} + 1} \)
Give your answer in the form \( a + b\sqrt{3} \) where \( a \) and \( b \) are integers.
Worked Solution
Step 1: Multiply by conjugate
๐ก Strategy: Multiply numerator and denominator by \( \sqrt{3} – 1 \) (the conjugate of the denominator).
โ Working:
\[ \frac{\sqrt{3} – 7}{\sqrt{3} + 1} \times \frac{\sqrt{3} – 1}{\sqrt{3} – 1} \]Step 2: Expand
โ Working:
Denominator: \( (\sqrt{3} + 1)(\sqrt{3} – 1) = 3 – 1 = 2 \)
Numerator: \( (\sqrt{3} – 7)(\sqrt{3} – 1) \)
\[ = \sqrt{3}\sqrt{3} – 1\sqrt{3} – 7\sqrt{3} + 7 \] \[ = 3 – 8\sqrt{3} + 7 \] \[ = 10 – 8\sqrt{3} \]Step 3: Simplify Fraction
โ Working:
\[ \frac{10 – 8\sqrt{3}}{2} \]Divide both terms by 2:
\[ 5 – 4\sqrt{3} \]Final Answer: \( 5 – 4\sqrt{3} \)
โ (Total: 4 marks)
Question 15 (9 marks total)
Point \( A \) lies on the curve \( y = x^2 + 5x + 8 \).
The \( x \)-coordinate of \( A \) is \( -4 \).
15(a) Show that the equation of the normal to the curve at \( A \) is \( 3y = x + 16 \). [5 marks]
15(b) The normal at \( A \) also intersects the curve at \( B \). Work out the \( x \)-coordinate of \( B \). [4 marks]
Worked Solution
Part (a): Equation of Normal
๐ก Strategy: 1. Find \( y \)-coordinate of A. 2. Differentiate to find gradient of tangent (\( m_t \)). 3. Use \( m_n = -1/m_t \) for normal gradient. 4. Use \( y – y_1 = m(x – x_1) \).
โ Working:
1. Coordinates of A:
\[ x = -4 \rightarrow y = (-4)^2 + 5(-4) + 8 \] \[ y = 16 – 20 + 8 = 4 \]Point A is \( (-4, 4) \).
2. Gradient of Tangent:
\[ \frac{dy}{dx} = 2x + 5 \] \[ \text{At } x = -4, \quad m_t = 2(-4) + 5 = -3 \]3. Gradient of Normal:
\[ m_n = \frac{-1}{-3} = \frac{1}{3} \]4. Equation:
\[ y – 4 = \frac{1}{3}(x – (-4)) \] \[ 3(y – 4) = x + 4 \] \[ 3y – 12 = x + 4 \] \[ 3y = x + 16 \]โ (Shown)
Part (b): Intersection Point B
๐ก Strategy: Solve the simultaneous equations of the curve and the normal line.
Line: \( y = \frac{x + 16}{3} \)
Curve: \( y = x^2 + 5x + 8 \)
โ Working:
\[ \frac{x + 16}{3} = x^2 + 5x + 8 \] \[ x + 16 = 3(x^2 + 5x + 8) \] \[ x + 16 = 3x^2 + 15x + 24 \]Rearrange to form quadratic:
\[ 0 = 3x^2 + 14x + 8 \]Factorise (we know \( x+4 \) is a factor because A is a solution):
\[ (3x + 2)(x + 4) = 0 \]Solutions:
\[ x = -4 \quad (\text{Point A}) \] \[ 3x = -2 \rightarrow x = -\frac{2}{3} \quad (\text{Point B}) \]Final Answer: \( x = -\frac{2}{3} \)
โ (Total: 4 marks)
Question 16 (4 marks)
The coefficient of the \( x^4 \) term in the expansion of \( (2x + a)^6 \) is 60.
Work out the possible values of \( a \).
Worked Solution
Step 1: Identify the relevant term
๐ก Strategy: In the binomial expansion of \( (A + B)^n \), the general term is \( \binom{n}{r} A^{n-r} B^r \). We want the term with \( x^4 \).
Here, \( A = 2x \), \( B = a \), and \( n = 6 \). To get \( x^4 \), we need \( (2x)^4 \). This means \( n-r = 4 \), so \( r = 2 \).
โ Working:
The term is:
\[ \binom{6}{2} (2x)^4 (a)^2 \]Calculate the combinations:
\[ \binom{6}{2} = \frac{6 \times 5}{2 \times 1} = 15 \]Step 2: Form the equation
โ Working:
Expand the parts:
\[ 15 \times (2^4 x^4) \times a^2 \] \[ 15 \times 16x^4 \times a^2 \] \[ 240 a^2 x^4 \]We are told the coefficient is 60. So:
\[ 240 a^2 = 60 \]โ (M1) Setting up equation
Step 3: Solve for a
โ Working:
\[ a^2 = \frac{60}{240} \] \[ a^2 = \frac{1}{4} \] \[ a = \pm \sqrt{\frac{1}{4}} \] \[ a = \pm \frac{1}{2} \]Final Answer: \( a = \frac{1}{2} \) and \( a = -\frac{1}{2} \)
โ (Total: 4 marks)
Question 17 (5 marks)
Solve the simultaneous equations:
\[ \begin{aligned} 1) \quad & 2a + b – c = 8 \\ 2) \quad & 4a – 3b – 2c = -9 \\ 3) \quad & 6a + 3b + c = 0 \end{aligned} \]Worked Solution
Step 1: Eliminate c
๐ก Strategy: Look at equations (1) and (3). One has \( -c \) and the other has \( +c \). Adding them will eliminate \( c \) immediately.
โ Working:
Add (1) and (3):
\[ (2a + b – c) + (6a + 3b + c) = 8 + 0 \] \[ 8a + 4b = 8 \]Divide by 4 to simplify:
\[ 2a + b = 2 \quad \text{— (Eq 4)} \]โ (M1) Eliminating one variable
Step 2: Create another equation without c
๐ก Strategy: We need to eliminate \( c \) from another pair. Let’s use Eq (2) and Eq (3). Multiply Eq (3) by 2 so we have \( +2c \) to match the \( -2c \) in Eq (2).
โ Working:
Eq (3) \( \times 2 \):
\[ 12a + 6b + 2c = 0 \]Add to Eq (2):
\[ (4a – 3b – 2c) + (12a + 6b + 2c) = -9 + 0 \] \[ 16a + 3b = -9 \quad \text{— (Eq 5)} \]Step 3: Solve for a and b
๐ก Strategy: Solve Eq (4) and Eq (5). From Eq (4), \( b = 2 – 2a \).
โ Working:
Substitute \( b = 2 – 2a \) into Eq (5):
\[ 16a + 3(2 – 2a) = -9 \] \[ 16a + 6 – 6a = -9 \] \[ 10a = -15 \] \[ a = -1.5 \]Now find \( b \):
\[ b = 2 – 2(-1.5) = 2 + 3 = 5 \]Step 4: Find c
โ Working:
Use Eq (3): \( 6a + 3b + c = 0 \)
\[ 6(-1.5) + 3(5) + c = 0 \] \[ -9 + 15 + c = 0 \] \[ 6 + c = 0 \] \[ c = -6 \]Final Answer: \( a = -1.5, \quad b = 5, \quad c = -6 \)
โ (Total: 5 marks)
Question 18 (3 marks)
Solve \( x^{-\frac{2}{3}} = 12\frac{1}{4} \)
Worked Solution
Step 1: Convert mixed number
โ Working:
\[ 12\frac{1}{4} = \frac{48+1}{4} = \frac{49}{4} \] \[ x^{-\frac{2}{3}} = \frac{49}{4} \]Step 2: Remove the negative index
๐ก Strategy: A negative power reciprocates the fraction. \( x^{-n} = \frac{1}{x^n} \), or if \( x^{-n} = \frac{A}{B} \), then \( x^n = \frac{B}{A} \).
โ Working:
\[ x^{\frac{2}{3}} = \frac{4}{49} \]Step 3: Solve for x
๐ก Strategy: To isolate \( x \), raise both sides to the power of \( \frac{3}{2} \) (the reciprocal of the current power).
โ Working:
\[ x = \left( \frac{4}{49} \right)^{\frac{3}{2}} \]This means: Square root, then Cube.
Square root:
\[ \sqrt{\frac{4}{49}} = \frac{2}{7} \]Cube:
\[ \left(\frac{2}{7}\right)^3 = \frac{8}{343} \]Final Answer: \( x = \frac{8}{343} \)
โ (Total: 3 marks)
Question 19 (4 marks)
\( f(x) = 2x^3 – 12x^2 + 25x – 11 \)
Use differentiation to show that \( f(x) \) is an increasing function for all values of \( x \).
Worked Solution
Step 1: Differentiate f(x)
๐ก Strategy: An increasing function has a positive gradient (\( f'(x) > 0 \)). First, find the derivative.
โ Working:
\[ f'(x) = 6x^2 – 24x + 25 \]โ (M1) Correct differentiation
Step 2: Prove the derivative is always positive
๐ก Strategy: Complete the square to show the quadratic expression is always greater than zero.
โ Working:
Factor out 6 from the \( x \) terms:
\[ 6(x^2 – 4x) + 25 \]Complete the square for \( x^2 – 4x \):
\[ 6((x – 2)^2 – 4) + 25 \] \[ 6(x – 2)^2 – 24 + 25 \] \[ 6(x – 2)^2 + 1 \]โ (M1) Completing the square
Step 3: Conclusion
๐ก Strategy: Explain why the result proves the function is increasing.
Since \( (x – 2)^2 \ge 0 \) for all real \( x \), then \( 6(x – 2)^2 + 1 \ge 1 \).
Therefore, \( f'(x) > 0 \) for all \( x \).
Hence, \( f(x) \) is an increasing function.
โ (Total: 4 marks)
Question 20 (5 marks total)
20(a) Show that \( 2\cos^2\theta \equiv 2 – 2\sin^2\theta \). [1 mark]
20(b) Hence, solve \( 2\cos^2\theta + 3\sin\theta = 3 \) for \( 0^\circ < \theta < 180^\circ \). [4 marks]
Worked Solution
Part (a): Identity
โ Working:
Use the identity \( \sin^2\theta + \cos^2\theta \equiv 1 \), which implies \( \cos^2\theta \equiv 1 – \sin^2\theta \).
\[ 2\cos^2\theta \equiv 2(1 – \sin^2\theta) \] \[ \equiv 2 – 2\sin^2\theta \]โ (Shown)
Part (b): Solve the equation
๐ก Strategy: Substitute the identity from part (a) into the equation to create a quadratic in terms of \( \sin\theta \).
โ Working:
\[ (2 – 2\sin^2\theta) + 3\sin\theta = 3 \]Rearrange to form a quadratic equal to zero:
\[ 2 – 2\sin^2\theta + 3\sin\theta – 3 = 0 \] \[ -2\sin^2\theta + 3\sin\theta – 1 = 0 \]Multiply by -1 to make the squared term positive:
\[ 2\sin^2\theta – 3\sin\theta + 1 = 0 \]โ (M1) Forming correct quadratic
Step 2: Factorise
โ Working:
Let \( y = \sin\theta \):
\[ 2y^2 – 3y + 1 = 0 \] \[ (2y – 1)(y – 1) = 0 \]So:
\[ \sin\theta = \frac{1}{2} \quad \text{or} \quad \sin\theta = 1 \]Step 3: Find angles
โ Working:
For \( \sin\theta = 0.5 \):
\[ \theta = 30^\circ \] \[ \theta = 180 – 30 = 150^\circ \]For \( \sin\theta = 1 \):
\[ \theta = 90^\circ \]Check range \( 0^\circ < \theta < 180^\circ \): All three are valid.
Final Answer: \( 30^\circ, 90^\circ, 150^\circ \)
โ (Total: 4 marks)