OCR MEI FP1 2015 June — Question 7 12 marks

Exam BoardOCR MEI
ModuleFP1 (Further Pure Mathematics 1)
Year2015
SessionJune
Marks12
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicIntegration with Partial Fractions
TypeRational function curve sketching
DifficultyStandard +0.8 This Further Maths question requires multiple sophisticated techniques: identifying asymptotes from rational functions, analyzing behavior near asymptotes, curve sketching with proper justification of limiting behavior, and solving a rational inequality. While each component is standard FP1 material, the combination and requirement to justify asymptotic approach elevates it above typical A-level questions.
Spec1.02g Inequalities: linear and quadratic in single variable1.02n Sketch curves: simple equations including polynomials1.02y Partial fractions: decompose rational functions

7 A curve has equation \(\mathrm { y } = \frac { ( 3 \mathrm { x } + 2 ) ( \mathrm { x } - 3 ) } { ( \mathrm { x } - 2 ) ( \mathrm { x } + 1 ) }\).
  1. Write down the equations of the three asymptotes and the coordinates of the points where the curve crosses the axes.
  2. Sketch the curve, justifying how it approaches the horizontal asymptote.
  3. Find the set of values of \(x\) for which \(y \geqslant 3\).

Question 7:
Part (i):
AnswerMarks Guidance
AnswerMarks Guidance
Asymptotes: \(y=3\), \(x=2\), \(x=-1\)B1
Crosses axes at \((0,3)\)B1 (both) Allow \(x=2\), \(x=-1\). Must see values for x and y if not written as co-ordinates
\(\left(-\dfrac{2}{3}, 0\right)\), \((3, 0)\)B1, B1 (both) Must see values for x and y if not written as co-ordinates
[4]
Part (ii):
AnswerMarks Guidance
AnswerMarks Guidance
Graph with intercepts labelledB1 Intercepts labelled (single figures on axes suffice)
Asymptotes correct and labelledB1 Allow \(y=3\) shown by intercept labelled at \((0,3)\) and \(x=2\) and \(x=-1\) likewise
Three correct branchesB2 Three correct branches (-1 each error). Any poorly illustrated asymptotic approaches penalised once only
When x is large and positive, graph approaches \(y=3\) from below, e.g. for \(x=100\), \(\frac{302\times97}{98\times101} = 2.9\ldots\)B1 Approaches to \(y=3\) justified. There must be a result for y
When x is large and negative, graph approaches \(y=3\) from above, e.g. for \(x=-100\), \(\frac{-298\times-103}{-102\times-99} = 3.03\ldots\)
[5]
Part (iii):
AnswerMarks Guidance
AnswerMarks Guidance
\(y \geq 3 \Rightarrow 0 \leq x < 2\) or \(x < -1\)B1 \(x < -1\)
B1B1\(0 \leq x < 2\) (B1 for \(0 < x < 2\) or \(0 \leq x \leq 2\)) isw any more shown
[3]
## Question 7:

### Part (i):

| Answer | Marks | Guidance |
|--------|-------|----------|
| Asymptotes: $y=3$, $x=2$, $x=-1$ | B1 | |
| Crosses axes at $(0,3)$ | B1 | (both) Allow $x=2$, $x=-1$. Must see values for x and y if not written as co-ordinates |
| $\left(-\dfrac{2}{3}, 0\right)$, $(3, 0)$ | B1, B1 | (both) Must see values for x and y if not written as co-ordinates |
| | **[4]** | |

### Part (ii):

| Answer | Marks | Guidance |
|--------|-------|----------|
| Graph with intercepts labelled | B1 | Intercepts labelled (single figures on axes suffice) |
| Asymptotes correct and labelled | B1 | Allow $y=3$ shown by intercept labelled at $(0,3)$ and $x=2$ and $x=-1$ likewise |
| Three correct branches | B2 | Three correct branches (-1 each error). Any poorly illustrated asymptotic approaches penalised once only |
| When x is large and positive, graph approaches $y=3$ from below, e.g. for $x=100$, $\frac{302\times97}{98\times101} = 2.9\ldots$ | B1 | Approaches to $y=3$ justified. There must be a result for y |
| When x is large and negative, graph approaches $y=3$ from above, e.g. for $x=-100$, $\frac{-298\times-103}{-102\times-99} = 3.03\ldots$ | | |
| | **[5]** | |

### Part (iii):

| Answer | Marks | Guidance |
|--------|-------|----------|
| $y \geq 3 \Rightarrow 0 \leq x < 2$ or $x < -1$ | B1 | $x < -1$ |
| | B1B1 | $0 \leq x < 2$ (B1 for $0 < x < 2$ or $0 \leq x \leq 2$) isw any more shown |
| | **[3]** | |

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7 A curve has equation $\mathrm { y } = \frac { ( 3 \mathrm { x } + 2 ) ( \mathrm { x } - 3 ) } { ( \mathrm { x } - 2 ) ( \mathrm { x } + 1 ) }$.\\
(i) Write down the equations of the three asymptotes and the coordinates of the points where the curve crosses the axes.\\
(ii) Sketch the curve, justifying how it approaches the horizontal asymptote.\\
(iii) Find the set of values of $x$ for which $y \geqslant 3$.

\hfill \mbox{\textit{OCR MEI FP1 2015 Q7 [12]}}