AQA FP1 2005 June — Question 9 13 marks

Exam BoardAQA
ModuleFP1 (Further Pure Mathematics 1)
Year2005
SessionJune
Marks13
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicCurve Sketching
TypeSimple rational function analysis
DifficultyStandard +0.3 This is a structured FP1 question on rational functions covering standard techniques: finding horizontal asymptotes by considering limits, explaining absence of vertical asymptotes via denominator analysis, and using the discriminant condition to find stationary points. While it requires multiple steps and connects the discriminant to stationary points (a moderately sophisticated insight for AS-level), each individual part follows well-established procedures taught in FP1, making it slightly easier than average overall.
Spec1.02k Simplify rational expressions: factorising, cancelling, algebraic division1.02n Sketch curves: simple equations including polynomials1.07n Stationary points: find maxima, minima using derivatives

9 The function f is defined by $$f ( x ) = \frac { x ^ { 2 } + 4 x } { x ^ { 2 } + 9 }$$
    1. The graph of \(y = \mathrm { f } ( x )\) has an asymptote which is parallel to the \(x\)-axis. Find the equation of this asymptote.
    2. Explain why the graph of \(y = \mathrm { f } ( x )\) has no asymptotes parallel to the \(y\)-axis.
  1. Show that the equation \(\mathrm { f } ( x ) = k\) has two equal roots if \(9 k ^ { 2 } - 9 k - 4 = 0\).
  2. Hence find the coordinates of the two stationary points on the graph of \(y = \mathrm { f } ( x )\).
    SurnameOther Names
    Centre NumberCandidate Number
    Candidate Signature
    General Certificate of Education
    June 2005
    Advanced Subsidiary Examination MATHEMATICS
    MFP1
    Unit Further Pure 1 ASSESSMENT and
    QUALIFICATIONS
    ALLIANCE Wednesday 22 June 2005 Afternoon Session Insert for use in Question 7.
    Fill in the boxes at the top of this page.
    Fasten this insert securely to your answer book.

Part (a)(i)
AnswerMarks Guidance
Asymptote is \(y = 1\)B1 1 mark
Part (a)(ii)
AnswerMarks Guidance
Denominator never zeroE2,1 2 marks
Part (a)(iii)
AnswerMarks Guidance
Part (b)
AnswerMarks Guidance
\(f(x) = k \Rightarrow (1-k)x^2 + 4x - 9k = 0\); Equal roots if \(16 + 36k(1-k) = 0\); ie if \(9k^2 - 9k - 4 = 0\)M1A1, m1, A1 4 marks
Part (c)
AnswerMarks Guidance
Solving quadratic for \(k\); \(k = -\frac{1}{3}\) or \(k = \frac{4}{3}\); \(4x^2 + 12x + 9 = 0\) or \(x^2 - 12x + 36 = 0\); SPs when \(x = -\frac{3}{2}, \ldots\) ;and when \(x = 6, \ldots\); SPs are \(\left(-\frac{3}{2}, -\frac{1}{3}\right)\) and \(\left(6, \frac{4}{3}\right)\)M1, A1, m1, A1, A1, A1 6 marks
Total: 13 marks
GRAND TOTAL: 75 marks
**Part (a)(i)**
| Asymptote is $y = 1$ | B1 | 1 mark | — |

**Part (a)(ii)**
| Denominator never zero | E2,1 | 2 marks | E1 if incomplete |

**Part (a)(iii)**
| — | — | — | — |

**Part (b)**
| $f(x) = k \Rightarrow (1-k)x^2 + 4x - 9k = 0$; Equal roots if $16 + 36k(1-k) = 0$; ie if $9k^2 - 9k - 4 = 0$ | M1A1, m1, A1 | 4 marks | convincingly shown (AG) |

**Part (c)**
| Solving quadratic for $k$; $k = -\frac{1}{3}$ or $k = \frac{4}{3}$; $4x^2 + 12x + 9 = 0$ or $x^2 - 12x + 36 = 0$; SPs when $x = -\frac{3}{2}, \ldots$ ;and when $x = 6, \ldots$; SPs are $\left(-\frac{3}{2}, -\frac{1}{3}\right)$ and $\left(6, \frac{4}{3}\right)$ | M1, A1, m1, A1, A1, A1 | 6 marks | NMS 2/2 |

**Total: 13 marks**

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**GRAND TOTAL: 75 marks**
9 The function f is defined by

$$f ( x ) = \frac { x ^ { 2 } + 4 x } { x ^ { 2 } + 9 }$$
\begin{enumerate}[label=(\alph*)]
\item \begin{enumerate}[label=(\roman*)]
\item The graph of $y = \mathrm { f } ( x )$ has an asymptote which is parallel to the $x$-axis. Find the equation of this asymptote.
\item Explain why the graph of $y = \mathrm { f } ( x )$ has no asymptotes parallel to the $y$-axis.
\end{enumerate}\item Show that the equation $\mathrm { f } ( x ) = k$ has two equal roots if $9 k ^ { 2 } - 9 k - 4 = 0$.
\item Hence find the coordinates of the two stationary points on the graph of $y = \mathrm { f } ( x )$.

\begin{center}
\begin{tabular}{|l|l|l|l|l|l|l|l|l|l|}
\hline
Surname & \multicolumn{9}{|c|}{Other Names} \\
\hline
\multicolumn{2}{|c|}{Centre Number} &  &  & \multicolumn{2}{|l|}{Candidate Number} &  &  &  &  \\
\hline
\multicolumn{3}{|c|}{Candidate Signature} &  &  &  &  &  &  &  \\
\hline
\end{tabular}
\end{center}

General Certificate of Education\\
June 2005\\
Advanced Subsidiary Examination

MATHEMATICS\\
MFP1\\
Unit Further Pure 1

ASSESSMENT and\\
QUALIFICATIONS\\
ALLIANCE

Wednesday 22 June 2005 Afternoon Session

Insert for use in Question 7.\\
Fill in the boxes at the top of this page.\\
Fasten this insert securely to your answer book.
\end{enumerate}

\hfill \mbox{\textit{AQA FP1 2005 Q9 [13]}}