AQA FP1 2011 June — Question 8 10 marks

Exam BoardAQA
ModuleFP1 (Further Pure Mathematics 1)
Year2011
SessionJune
Marks10
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicPartial Fractions
TypeRational curve sketching with asymptotes and inequalities
DifficultyStandard +0.3 This is a straightforward FP1 curve sketching question requiring identification of vertical asymptotes at x=±2 and horizontal asymptote at y=0, plus a basic sketch. Part (b) involves solving a rational inequality using the sketch, which is routine once the curve is drawn. The techniques are standard and require no novel insight.
Spec1.02g Inequalities: linear and quadratic in single variable1.02o Sketch reciprocal curves: y=a/x and y=a/x^2

8 A curve has equation \(y = \frac { 1 } { x ^ { 2 } - 4 }\).
    1. Write down the equations of the three asymptotes of the curve.
    2. Sketch the curve, showing the coordinates of any points of intersection with the coordinate axes.
  1. Hence, or otherwise, solve the inequality $$\frac { 1 } { x ^ { 2 } - 4 } < - 2$$

Question 8:
Part (a)(i):
AnswerMarks Guidance
Answer/WorkingMarks Guidance
Asymptotes \(x = -2\), \(x = 2\), \(y = 0\)\(\text{B1} \times 3\)
Total3
Part (a)(ii):
AnswerMarks Guidance
Answer/WorkingMarks Guidance
Middle branch generally correctB1 Allow if max pt not in right place
Other branches generally correctB1
All branches approaching asympsB1 Asymps must be shown correctly on diagram or elsewhere; B0 if any other intersections are shown
Intersection at \(\left(0, -\frac{1}{4}\right)\) indicatedB1
Total4
Part (b):
AnswerMarks Guidance
Answer/WorkingMarks Guidance
\(y = -2\) when \(x = \pm\sqrt{3.5}\)B1 Allow NMS
Sol'n \(-2 < x < -\sqrt{3.5}\), \(\sqrt{3.5} < x < 2\)B2,1 Condone dec approx'n for \(\sqrt{3.5}\); B1 if \(\leq\) used instead of \(<\)
Total3
## Question 8:

### Part (a)(i):
| Answer/Working | Marks | Guidance |
|---|---|---|
| Asymptotes $x = -2$, $x = 2$, $y = 0$ | $\text{B1} \times 3$ | |
| **Total** | **3** | |

### Part (a)(ii):
| Answer/Working | Marks | Guidance |
|---|---|---|
| Middle branch generally correct | B1 | Allow if max pt not in right place |
| Other branches generally correct | B1 | |
| All branches approaching asymps | B1 | Asymps must be shown correctly on diagram or elsewhere; B0 if any other intersections are shown |
| Intersection at $\left(0, -\frac{1}{4}\right)$ indicated | B1 | |
| **Total** | **4** | |

### Part (b):
| Answer/Working | Marks | Guidance |
|---|---|---|
| $y = -2$ when $x = \pm\sqrt{3.5}$ | B1 | Allow NMS |
| Sol'n $-2 < x < -\sqrt{3.5}$, $\sqrt{3.5} < x < 2$ | B2,1 | Condone dec approx'n for $\sqrt{3.5}$; B1 if $\leq$ used instead of $<$ |
| **Total** | **3** | |

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8 A curve has equation $y = \frac { 1 } { x ^ { 2 } - 4 }$.
\begin{enumerate}[label=(\alph*)]
\item \begin{enumerate}[label=(\roman*)]
\item Write down the equations of the three asymptotes of the curve.
\item Sketch the curve, showing the coordinates of any points of intersection with the coordinate axes.
\end{enumerate}\item Hence, or otherwise, solve the inequality

$$\frac { 1 } { x ^ { 2 } - 4 } < - 2$$
\end{enumerate}

\hfill \mbox{\textit{AQA FP1 2011 Q8 [10]}}