AQA FP3 2012 June — Question 5 7 marks

Exam BoardAQA
ModuleFP3 (Further Pure Mathematics 3)
Year2012
SessionJune
Marks7
PaperDownload PDF ↗
TopicIntegration by Parts
TypeImproper integral with parts
DifficultyStandard +0.8 This is a Further Maths question requiring two applications of integration by parts for part (a), then careful handling of an improper integral with limits approaching infinity in part (b). While the technique is standard for FP3, the combination of repeated integration by parts plus rigorous treatment of the limiting process elevates this above typical A-level questions.
Spec1.08i Integration by parts4.08c Improper integrals: infinite limits or discontinuous integrands

5
  1. Find \(\int x ^ { 2 } \mathrm { e } ^ { - x } \mathrm {~d} x\).
  2. Hence evaluate \(\int _ { 0 } ^ { \infty } x ^ { 2 } \mathrm { e } ^ { - x } \mathrm {~d} x\), showing the limiting process used.

5
\begin{enumerate}[label=(\alph*)]
\item Find $\int x ^ { 2 } \mathrm { e } ^ { - x } \mathrm {~d} x$.
\item Hence evaluate $\int _ { 0 } ^ { \infty } x ^ { 2 } \mathrm { e } ^ { - x } \mathrm {~d} x$, showing the limiting process used.
\end{enumerate}

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