CAIE P2 2007 November — Question 8 10 marks

Exam BoardCAIE
ModuleP2 (Pure Mathematics 2)
Year2007
SessionNovember
Marks10
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicNumerical integration
TypeTrapezium rule with stated number of strips
DifficultyModerate -0.3 This is a straightforward multi-part question testing standard P2 techniques: differentiation using product rule to find a maximum, verifying a tangent passes through a point, and applying the trapezium rule with clear instructions. All parts are routine applications of learned methods with no novel problem-solving required, making it slightly easier than average.
Spec1.07j Differentiate exponentials: e^(kx) and a^(kx)1.07m Tangents and normals: gradient and equations1.07n Stationary points: find maxima, minima using derivatives1.07q Product and quotient rules: differentiation1.09f Trapezium rule: numerical integration

8 \includegraphics[max width=\textwidth, alt={}, center]{8f815127-61b2-4a7f-8687-747950ea6597-3_693_1061_262_541} The diagram shows the curve \(y = x ^ { 2 } \mathrm { e } ^ { - x }\) and its maximum point \(M\).
  1. Find the \(x\)-coordinate of \(M\).
  2. Show that the tangent to the curve at the point where \(x = 1\) passes through the origin.
  3. Use the trapezium rule, with two intervals, to estimate the value of $$\int _ { 1 } ^ { 3 } x ^ { 2 } \mathrm { e } ^ { - x } \mathrm {~d} x$$ giving your answer correct to 2 decimal places.

(i)
AnswerMarks Guidance
Differentiate using product or quotient ruleM1
Obtain derivative in any correct formA1
Equate derivative to zero and solve for \(x\)M1
Obtain answer \(x = 2\) correctly, with no other solutionA1 [4]
(ii)
AnswerMarks Guidance
Find the gradient of the curve when \(x = 1\), must be simplified, allow 0.368B1
Form the equation of the tangent when \(x = 1\)M1
Show that it passes through the originA1 [3]
(iii)
AnswerMarks Guidance
State or imply correct ordinates \(0.36787\ldots, 0.54134\ldots, 0.44808\ldots\)B1
Use correct formula, or equivalent, correctly with \(h = 1\) and three ordinatesM1
Obtain answer 0.95 with no errors seenA1 [3]
**(i)**

Differentiate using product or quotient rule | M1 |
Obtain derivative in any correct form | A1 |
Equate derivative to zero and solve for $x$ | M1 |
Obtain answer $x = 2$ correctly, with no other solution | A1 | [4]

**(ii)**

Find the gradient of the curve when $x = 1$, must be simplified, allow 0.368 | B1 |
Form the equation of the tangent when $x = 1$ | M1 |
Show that it passes through the origin | A1 | [3]

**(iii)**

State or imply correct ordinates $0.36787\ldots, 0.54134\ldots, 0.44808\ldots$ | B1 |
Use correct formula, or equivalent, correctly with $h = 1$ and three ordinates | M1 |
Obtain answer 0.95 with no errors seen | A1 | [3]
8\\
\includegraphics[max width=\textwidth, alt={}, center]{8f815127-61b2-4a7f-8687-747950ea6597-3_693_1061_262_541}

The diagram shows the curve $y = x ^ { 2 } \mathrm { e } ^ { - x }$ and its maximum point $M$.\\
(i) Find the $x$-coordinate of $M$.\\
(ii) Show that the tangent to the curve at the point where $x = 1$ passes through the origin.\\
(iii) Use the trapezium rule, with two intervals, to estimate the value of

$$\int _ { 1 } ^ { 3 } x ^ { 2 } \mathrm { e } ^ { - x } \mathrm {~d} x$$

giving your answer correct to 2 decimal places.

\hfill \mbox{\textit{CAIE P2 2007 Q8 [10]}}