OCR MEI FP1 2005 June — Question 8 14 marks

Exam BoardOCR MEI
ModuleFP1 (Further Pure Mathematics 1)
Year2005
SessionJune
Marks14
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicIntegration with Partial Fractions
TypeRational function curve sketching
DifficultyChallenging +1.2 This is a Further Maths question requiring curve sketching of a rational function with asymptote analysis and inequality solving. While it involves multiple techniques (finding asymptotes, end behavior, sketching, and solving a rational inequality), each component is relatively standard for FP1. The repeated factor in the denominator adds some complexity, but the overall approach is methodical rather than requiring novel insight. Harder than average A-level due to being Further Maths content, but routine within that context.
Spec1.02g Inequalities: linear and quadratic in single variable1.02n Sketch curves: simple equations including polynomials

8 A curve has equation \(y = \frac { x ^ { 2 } - 4 } { ( 3 x - 2 ) ^ { 2 } }\).
  1. Find the equations of the asymptotes.
  2. Describe the behaviour of the curve for large positive and large negative values of \(x\), justifying your description.
  3. Sketch the curve.
  4. Solve the inequality \(\frac { x ^ { 2 } - 4 } { ( 3 x - 2 ) ^ { 2 } } \geqslant - 1\).

Question 8:
Part (i)
AnswerMarks Guidance
\(x = \frac{2}{3}\) and \(y = \frac{1}{9}\)B1, B1 [2] \(-1\) if any others given. Accept min 2 s.f. accuracy
Part (ii)
AnswerMarks Guidance
Large positive \(x\), \(y \to \frac{1}{9}^+\) (e.g. consider \(x = 100\))M1 Approaches horizontal asymptote, not inconsistent with their (i)
Large negative \(x\), \(y \to \frac{1}{9}^-\) (e.g. consider \(x = -100\))A1 Correct approaches
E1 [3]Reasonable attempt to justify approaches
Part (iii)
AnswerMarks Guidance
Curve with \(x = \frac{2}{3}\) shown with correct approachesB1(ft)
\(y = \frac{1}{9}\) shown with correct approaches (from below on left, above on right)B1(ft) 1 for each branch, consistent with horizontal asymptote in (i) or (ii)
\((2, 0),\ (-2, 0)\) and \((0, -1)\) shownB1(ft), B1, B1 [5] Both \(x\) intercepts and \(y\) intercept. Give these marks if coordinates shown in workings, even if not shown on graph
Part (iv)
AnswerMarks Guidance
\(-1 = \frac{x^2-4}{(3x-2)^2} \Rightarrow -9x^2+12x-4 = x^2-4\)
\(\Rightarrow 10x^2 - 12x = 0\)
\(\Rightarrow 2x(5x-6) = 0\)
\(\Rightarrow x = 0\) or \(x = \frac{6}{5}\)M1 Reasonable attempt at solving inequality
From sketch: \(y \geq -1\) for \(x \leq 0\) and \(x \geq \frac{6}{5}\)A1 Both values – give for seeing \(0\) and \(\frac{6}{5}\), even if inequalities are wrong
B1For \(x \leq 0\)
F1 [4]Lose only one mark if any strict inequalities given
## Question 8:

### Part (i)
$x = \frac{2}{3}$ and $y = \frac{1}{9}$ | B1, B1 **[2]** | $-1$ if any others given. Accept min 2 s.f. accuracy

### Part (ii)
Large positive $x$, $y \to \frac{1}{9}^+$ (e.g. consider $x = 100$) | M1 | Approaches horizontal asymptote, not inconsistent with their (i)

Large negative $x$, $y \to \frac{1}{9}^-$ (e.g. consider $x = -100$) | A1 | Correct approaches

| E1 **[3]** | Reasonable attempt to justify approaches

### Part (iii)
Curve with $x = \frac{2}{3}$ shown with correct approaches | B1(ft) | —

$y = \frac{1}{9}$ shown with correct approaches (from below on left, above on right) | B1(ft) | 1 for each branch, consistent with horizontal asymptote in (i) or (ii)

$(2, 0),\ (-2, 0)$ and $(0, -1)$ shown | B1(ft), B1, B1 **[5]** | Both $x$ intercepts and $y$ intercept. Give these marks if coordinates shown in workings, even if not shown on graph

### Part (iv)
$-1 = \frac{x^2-4}{(3x-2)^2} \Rightarrow -9x^2+12x-4 = x^2-4$ | — | —

$\Rightarrow 10x^2 - 12x = 0$ | — | —

$\Rightarrow 2x(5x-6) = 0$ | — | —

$\Rightarrow x = 0$ or $x = \frac{6}{5}$ | M1 | Reasonable attempt at solving inequality

From sketch: $y \geq -1$ for $x \leq 0$ and $x \geq \frac{6}{5}$ | A1 | Both values – give for seeing $0$ and $\frac{6}{5}$, even if inequalities are wrong

| B1 | For $x \leq 0$

| F1 **[4]** | Lose only one mark if any strict inequalities given

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8 A curve has equation $y = \frac { x ^ { 2 } - 4 } { ( 3 x - 2 ) ^ { 2 } }$.\\
(i) Find the equations of the asymptotes.\\
(ii) Describe the behaviour of the curve for large positive and large negative values of $x$, justifying your description.\\
(iii) Sketch the curve.\\
(iv) Solve the inequality $\frac { x ^ { 2 } - 4 } { ( 3 x - 2 ) ^ { 2 } } \geqslant - 1$.

\hfill \mbox{\textit{OCR MEI FP1 2005 Q8 [14]}}