OCR MEI FP1 2014 June — Question 7 12 marks

Exam BoardOCR MEI
ModuleFP1 (Further Pure Mathematics 1)
Year2014
SessionJune
Marks12
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicPolynomial Division & Manipulation
TypeSolving Inequalities with Rational Functions
DifficultyStandard +0.8 This FP1 question requires understanding of rational functions including asymptotes, curve sketching, and solving rational inequalities by sign analysis. While the individual components (finding intercepts, asymptotes) are routine, part (iv) requires systematic analysis of sign changes across multiple discontinuities, which is more demanding than standard A-level work and typical of Further Maths.
Spec1.02g Inequalities: linear and quadratic in single variable1.02i Represent inequalities: graphically on coordinate plane1.02k Simplify rational expressions: factorising, cancelling, algebraic division1.02n Sketch curves: simple equations including polynomials1.02y Partial fractions: decompose rational functions

7 A curve has equation \(y = \frac { x ^ { 2 } - 5 } { ( x + 3 ) ( x - 2 ) ( a x - 1 ) }\), where \(a\) is a constant.
  1. Find the coordinates of the points where the curve crosses the \(x\)-axis and the \(y\)-axis.
  2. You are given that the curve has a vertical asymptote at \(x = \frac { 1 } { 2 }\). Write down the value of \(a\) and the equations of the other asymptotes.
  3. Sketch the curve.
  4. Find the set of values of \(x\) for which \(y > 0\).

Question 7(i):
AnswerMarks Guidance
\(\left(0, -\dfrac{5}{6}\right)\)B1 Allow for both \(x=0\) and \(y=-\dfrac{5}{6}\) seen
\((\sqrt{5},\, 0),\;(-\sqrt{5},\, 0)\)B1 [2] Allow \((\pm\sqrt{5}, 0)\) or for both \(y=0\) and \(x=\pm\sqrt{5}\) seen
Question 7(ii):
AnswerMarks Guidance
\(a = 2\)B1
\(y = 0\)B1
\(x = -3,\; x = 2\)B1 [3] Must be two equations
Question 7(iii):
AnswerMarks Guidance
Graph with two outer branches correctly placedB1
Inner branches correctly placedB1 For good drawing, dep all 3 marks above
Correct asymptotes and intercepts labelledB1 Look for clear maximum point on right-hand branch
Condone turning points in \(-\sqrt{5} < x < \dfrac{1}{2},\; y < 0\)B1 [4]
Question 7(iv):
AnswerMarks Guidance
\(-3 < x < -\sqrt{5},\quad \dfrac{1}{2} < x < 2,\quad x > \sqrt{5}\)B3 [3] One mark for each. Strict inequalities. Allow \(2.24\) for \(\sqrt{5}\). (If B3 then \(-1\) if more than 3 inequalities)
## Question 7(i):

$\left(0, -\dfrac{5}{6}\right)$ | B1 | Allow for both $x=0$ and $y=-\dfrac{5}{6}$ seen

$(\sqrt{5},\, 0),\;(-\sqrt{5},\, 0)$ | B1 **[2]** | Allow $(\pm\sqrt{5}, 0)$ or for both $y=0$ and $x=\pm\sqrt{5}$ seen

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## Question 7(ii):

$a = 2$ | B1 |

$y = 0$ | B1 |

$x = -3,\; x = 2$ | B1 **[3]** | Must be two equations

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## Question 7(iii):

Graph with two outer branches correctly placed | B1 |

Inner branches correctly placed | B1 | For good drawing, dep all 3 marks above

Correct asymptotes and intercepts labelled | B1 | Look for clear maximum point on right-hand branch

Condone turning points in $-\sqrt{5} < x < \dfrac{1}{2},\; y < 0$ | B1 **[4]** |

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## Question 7(iv):

$-3 < x < -\sqrt{5},\quad \dfrac{1}{2} < x < 2,\quad x > \sqrt{5}$ | B3 **[3]** | One mark for each. Strict inequalities. Allow $2.24$ for $\sqrt{5}$. (If B3 then $-1$ if more than 3 inequalities)
7 A curve has equation $y = \frac { x ^ { 2 } - 5 } { ( x + 3 ) ( x - 2 ) ( a x - 1 ) }$, where $a$ is a constant.\\
(i) Find the coordinates of the points where the curve crosses the $x$-axis and the $y$-axis.\\
(ii) You are given that the curve has a vertical asymptote at $x = \frac { 1 } { 2 }$. Write down the value of $a$ and the equations of the other asymptotes.\\
(iii) Sketch the curve.\\
(iv) Find the set of values of $x$ for which $y > 0$.

\hfill \mbox{\textit{OCR MEI FP1 2014 Q7 [12]}}