AQA Further Paper 1 2023 June — Question 11 7 marks

Exam BoardAQA
ModuleFurther Paper 1 (Further Paper 1)
Year2023
SessionJune
Marks7
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicCurve Sketching
TypeReflection or vertical transformation
DifficultyStandard +0.8 This is a multi-step Further Maths question requiring factorisation of a cubic (likely needing factor theorem), solving a cubic inequality, then applying two transformations and solving another inequality. While each individual step is standard, the combination of techniques and the transformation work in part (b) requires careful algebraic manipulation and understanding of function transformations, placing it moderately above average difficulty.
Spec1.02g Inequalities: linear and quadratic in single variable1.02j Manipulate polynomials: expanding, factorising, division, factor theorem1.02w Graph transformations: simple transformations of f(x)

The function f is defined by $$f(x) = 4x^3 - 8x^2 - 51x - 45 \quad (x \in \mathbb{R})$$
    1. Fully factorise \(f(x)\) [2 marks]
    2. Hence, solve the inequality \(f(x) < 0\) [2 marks]
  1. The graph of \(y = f(x)\) is translated by the vector \(\begin{pmatrix} 7 \\ 0 \end{pmatrix}\) The new graph is then reflected in the \(x\)-axis, to give the graph of \(y = g(x)\) Solve the inequality \(g(x) \leq 0\) [3 marks]

Question 11:

AnswerMarks Guidance
11(a)(i)Obtains one factor of f(x) 1.1a
Deduces the correct factorisation2.2a A1
Subtotal2
QMarking instructions AO

AnswerMarks Guidance
11(a)(ii)Deduces that x<5 2.2a
x<−3,−3 < x<5
(𝑥𝑥)2< 2
Obtains a completely correct
AnswerMarks Guidance
solution to the inequality1.1b A1
Subtotal2
QMarking instructions AO

AnswerMarks
11(b)Obtains ±5.5 or ±12
ft 7 + their critical values from
AnswerMarks Guidance
(a)(ii)2.2a M1
2
If g(x)≤0,
x=11 or x≥12
2
Obtains 5.5 and 12
ft 7 + their critical values from
AnswerMarks Guidance
(a)(ii)2.2a A1F
Obtains a completely correct
AnswerMarks Guidance
solution to the inequality1.1b A1
Subtotal3
Question total7
QMarking instructions AO
Question 11:
--- 11(a)(i) ---
11(a)(i) | Obtains one factor of f(x) | 1.1a | M1 | f(x)=( x−5 )( 2x+3 )2
Deduces the correct factorisation | 2.2a | A1
Subtotal | 2
Q | Marking instructions | AO | Marks | Typical solution
--- 11(a)(ii) ---
11(a)(ii) | Deduces that x<5 | 2.2a | M1 | If f 0,
x<−3,−3 < x<5
(𝑥𝑥)2< 2
Obtains a completely correct
solution to the inequality | 1.1b | A1
Subtotal | 2
Q | Marking instructions | AO | Marks | Typical solution
--- 11(b) ---
11(b) | Obtains ±5.5 or ±12
ft 7 + their critical values from
(a)(ii) | 2.2a | M1 | g(x)=0⇒ x=11,x=12
2
If g(x)≤0,
x=11 or x≥12
2
Obtains 5.5 and 12
ft 7 + their critical values from
(a)(ii) | 2.2a | A1F
Obtains a completely correct
solution to the inequality | 1.1b | A1
Subtotal | 3
Question total | 7
Q | Marking instructions | AO | Marks | Typical solution
The function f is defined by
$$f(x) = 4x^3 - 8x^2 - 51x - 45 \quad (x \in \mathbb{R})$$

\begin{enumerate}[label=(\alph*)]
\item \begin{enumerate}[label=(\roman*)]
\item Fully factorise $f(x)$
[2 marks]

\item Hence, solve the inequality $f(x) < 0$
[2 marks]
\end{enumerate}

\item The graph of $y = f(x)$ is translated by the vector $\begin{pmatrix} 7 \\ 0 \end{pmatrix}$

The new graph is then reflected in the $x$-axis, to give the graph of $y = g(x)$

Solve the inequality $g(x) \leq 0$
[3 marks]
\end{enumerate}

\hfill \mbox{\textit{AQA Further Paper 1 2023 Q11 [7]}}