CAIE P2 2023 June — Question 3 7 marks

Exam BoardCAIE
ModuleP2 (Pure Mathematics 2)
Year2023
SessionJune
Marks7
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicFixed Point Iteration
TypeDerive equation from integral condition
DifficultyStandard +0.3 Part (a) requires straightforward integration of an exponential function and algebraic rearrangement to reach the given form—standard P2 technique. Part (b) applies a given iterative formula with clear instructions, requiring only careful calculator work. This is a routine multi-part question slightly easier than average due to its procedural nature and explicit guidance.
Spec1.06a Exponential function: a^x and e^x graphs and properties1.08d Evaluate definite integrals: between limits1.09c Simple iterative methods: x_{n+1} = g(x_n), cobweb and staircase diagrams

3 It is given that \(\int _ { 0 } ^ { a } \left( 3 \mathrm { e } ^ { 2 x } - 1 \right) \mathrm { d } x = 12\), where \(a\) is a positive constant.
  1. Show that \(a = \frac { 1 } { 2 } \ln \left( 9 + \frac { 2 } { 3 } a \right)\).
  2. Use an iterative formula, based on the equation in (a), to find the value of \(a\) correct to 4 significant figures. Use an initial value of 1 and give the result of each iteration to 6 significant figures. [3]

Question 3(a):
AnswerMarks Guidance
AnswerMarks Guidance
Integrate to obtain the form \(k_1e^{2x} + k_2x\)*M1 Where \(k_1k_2 \neq 0\)
Obtain correct \(\frac{3}{2}e^{2x} - x\)A1
Use limits correctly and attempt rearrangement at least as far as \(e^{2a} = \ldots\)DM1 Must be equated to 12 and simplified using a correct method. Do not condone verification.
Confirm given result \(a = \frac{1}{2}\ln(9 + \frac{2}{3}a)\) with sufficient detailA1 AG
Question 3(b):
AnswerMarks Guidance
AnswerMarks Guidance
Use iteration process correctly at least onceM1 Need to see 1.13434 and 1.13895
Obtain final answer 1.139A1 Final answer needed to exactly 4 sf
Show sufficient iterations to 6 sf to justify answer or show a sign change in interval [1.1385, 1.1395]A1
## Question 3(a):

| Answer | Marks | Guidance |
|--------|-------|----------|
| Integrate to obtain the form $k_1e^{2x} + k_2x$ | *M1 | Where $k_1k_2 \neq 0$ |
| Obtain correct $\frac{3}{2}e^{2x} - x$ | A1 | |
| Use limits correctly and attempt rearrangement at least as far as $e^{2a} = \ldots$ | DM1 | Must be equated to 12 and simplified using a correct method. Do not condone verification. |
| Confirm given result $a = \frac{1}{2}\ln(9 + \frac{2}{3}a)$ with sufficient detail | A1 | AG |

## Question 3(b):

| Answer | Marks | Guidance |
|--------|-------|----------|
| Use iteration process correctly at least once | M1 | Need to see 1.13434 and 1.13895 |
| Obtain final answer 1.139 | A1 | Final answer needed to exactly 4 sf |
| Show sufficient iterations to 6 sf to justify answer or show a sign change in interval [1.1385, 1.1395] | A1 | |
3 It is given that $\int _ { 0 } ^ { a } \left( 3 \mathrm { e } ^ { 2 x } - 1 \right) \mathrm { d } x = 12$, where $a$ is a positive constant.
\begin{enumerate}[label=(\alph*)]
\item Show that $a = \frac { 1 } { 2 } \ln \left( 9 + \frac { 2 } { 3 } a \right)$.
\item Use an iterative formula, based on the equation in (a), to find the value of $a$ correct to 4 significant figures. Use an initial value of 1 and give the result of each iteration to 6 significant figures. [3]
\end{enumerate}

\hfill \mbox{\textit{CAIE P2 2023 Q3 [7]}}