CAIE P2 2024 November — Question 5 8 marks

Exam BoardCAIE
ModuleP2 (Pure Mathematics 2)
Year2024
SessionNovember
Marks8
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicStandard Integrals and Reverse Chain Rule
TypeFind constant from definite integral
DifficultyStandard +0.3 This is a straightforward multi-step problem requiring standard integration of 1/(2x+1), evaluation of definite integral, algebraic rearrangement to the given form, and then iterative solution. All techniques are routine for P2 level with no novel insight required, making it slightly easier than average.
Spec1.08c Integrate e^(kx), 1/x, sin(kx), cos(kx)1.09c Simple iterative methods: x_{n+1} = g(x_n), cobweb and staircase diagrams

5 It is given that \(\int _ { a } ^ { a ^ { 3 } } \frac { 10 } { 2 x + 1 } \mathrm {~d} x = 7\), where \(a\) is a constant greater than 1 .
  1. Show that \(a = \sqrt [ 3 ] { 0.5 \mathrm { e } ^ { 1.4 } ( 2 a + 1 ) - 0.5 }\). \includegraphics[max width=\textwidth, alt={}, center]{dcc483e9-630e-4f02-ad8c-4a27c0720fc6-08_2718_35_107_2011} \includegraphics[max width=\textwidth, alt={}, center]{dcc483e9-630e-4f02-ad8c-4a27c0720fc6-09_2725_35_99_20}
  2. Use an iterative formula, based on the equation in part (a), to find the value of \(a\) correct to 3 significant figures. Use an initial value of 2 and give the result of each iteration to 5 significant figures.

Question 5(a):
AnswerMarks Guidance
AnswerMark Guidance
Obtain integral of form \(k\ln(2x+1)\)*M1
Obtain correct \(5\ln(2x+1)\)A1
Apply limits correctly and equate to 7DM1
Apply appropriate logarithm property to reach at least \(a^3 = \ldots\)DM1
Confirm \(a = \sqrt[3]{0.5e^{1.4}(2a+1)} - 0.5\)A1 AG – necessary detail needed
Question 5(b):
AnswerMarks Guidance
AnswerMark Guidance
Use iterative process correctly at least onceM1
Obtain final answer \(2.18\)A1 Answer required to exactly 3 sf
Show sufficient iterations to 5 sf to justify answer or show a sign change in the interval \([2.175, 2.185]\)A1
## Question 5(a):

| Answer | Mark | Guidance |
|--------|------|----------|
| Obtain integral of form $k\ln(2x+1)$ | *M1 | |
| Obtain correct $5\ln(2x+1)$ | A1 | |
| Apply limits correctly and equate to 7 | DM1 | |
| Apply appropriate logarithm property to reach at least $a^3 = \ldots$ | DM1 | |
| Confirm $a = \sqrt[3]{0.5e^{1.4}(2a+1)} - 0.5$ | A1 | AG – necessary detail needed |

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## Question 5(b):

| Answer | Mark | Guidance |
|--------|------|----------|
| Use iterative process correctly at least once | M1 | |
| Obtain final answer $2.18$ | A1 | Answer required to exactly 3 sf |
| Show sufficient iterations to 5 sf to justify answer or show a sign change in the interval $[2.175, 2.185]$ | A1 | |

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5 It is given that $\int _ { a } ^ { a ^ { 3 } } \frac { 10 } { 2 x + 1 } \mathrm {~d} x = 7$, where $a$ is a constant greater than 1 .
\begin{enumerate}[label=(\alph*)]
\item Show that $a = \sqrt [ 3 ] { 0.5 \mathrm { e } ^ { 1.4 } ( 2 a + 1 ) - 0.5 }$.\\

\includegraphics[max width=\textwidth, alt={}, center]{dcc483e9-630e-4f02-ad8c-4a27c0720fc6-08_2718_35_107_2011}\\
\includegraphics[max width=\textwidth, alt={}, center]{dcc483e9-630e-4f02-ad8c-4a27c0720fc6-09_2725_35_99_20}
\item Use an iterative formula, based on the equation in part (a), to find the value of $a$ correct to 3 significant figures. Use an initial value of 2 and give the result of each iteration to 5 significant figures.
\end{enumerate}

\hfill \mbox{\textit{CAIE P2 2024 Q5 [8]}}