CAIE P2 2011 June — Question 5 7 marks

Exam BoardCAIE
ModuleP2 (Pure Mathematics 2)
Year2011
SessionJune
Marks7
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicProduct & Quotient Rules
TypeFind gradient at point
DifficultyModerate -0.8 This is a straightforward application of product rule (part i) and quotient rule (part ii) followed by direct substitution. Both are standard textbook exercises with no problem-solving required—students simply apply memorized differentiation rules and evaluate at the given point. Easier than average A-level questions.
Spec1.07l Derivative of ln(x): and related functions1.07q Product and quotient rules: differentiation1.07r Chain rule: dy/dx = dy/du * du/dx and connected rates

5 Find the value of \(\frac { \mathrm { d } y } { \mathrm {~d} x }\) when \(x = 4\) in each of the following cases:
  1. \(y = x \ln ( x - 3 )\),
  2. \(y = \frac { x - 1 } { x + 1 }\).

AnswerMarks Guidance
(i) Differentiate \(\ln(x-3)\) to obtain \(\frac{1}{x-3}\)B1
Attempt to use product ruleM1
Obtain \(\ln(x-3) + \frac{x}{x-3}\) or equivalentA1
Substitute \(4\) to obtain \(4\)A1 [4]
(ii) Use correct quotient or product ruleM1
Obtain correct derivative in any form, e.g. \(\frac{(x+1)-(x-1)}{(x+1)^2}\)A1
Substitute \(4\) to obtain \(\frac{2}{25}\)A1 [3]
**(i)** Differentiate $\ln(x-3)$ to obtain $\frac{1}{x-3}$ | B1 |
Attempt to use product rule | M1 |
Obtain $\ln(x-3) + \frac{x}{x-3}$ or equivalent | A1 |
Substitute $4$ to obtain $4$ | A1 | [4]

**(ii)** Use correct quotient or product rule | M1 |
Obtain correct derivative in any form, e.g. $\frac{(x+1)-(x-1)}{(x+1)^2}$ | A1 |
Substitute $4$ to obtain $\frac{2}{25}$ | A1 | [3]
5 Find the value of $\frac { \mathrm { d } y } { \mathrm {~d} x }$ when $x = 4$ in each of the following cases:\\
(i) $y = x \ln ( x - 3 )$,\\
(ii) $y = \frac { x - 1 } { x + 1 }$.

\hfill \mbox{\textit{CAIE P2 2011 Q5 [7]}}