CAIE FP1 2019 June — Question 4

Exam BoardCAIE
ModuleFP1 (Further Pure Mathematics 1)
Year2019
SessionJune
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicIntegration by Parts

4 It is given that, for \(n \geqslant 0\), $$I _ { n } = \int _ { 0 } ^ { 1 } x ^ { n } \mathrm { e } ^ { x ^ { 3 } } \mathrm {~d} x$$
  1. Show that \(I _ { 2 } = \frac { 1 } { 3 } ( \mathrm { e } - 1 )\).
  2. Show that, for \(n \geqslant 3\), $$3 I _ { n } = \mathrm { e } - ( n - 2 ) I _ { n - 3 }$$
  3. Hence find the exact value of \(I _ { 8 }\).

4 It is given that, for $n \geqslant 0$,

$$I _ { n } = \int _ { 0 } ^ { 1 } x ^ { n } \mathrm { e } ^ { x ^ { 3 } } \mathrm {~d} x$$

(i) Show that $I _ { 2 } = \frac { 1 } { 3 } ( \mathrm { e } - 1 )$.\\

(ii) Show that, for $n \geqslant 3$,

$$3 I _ { n } = \mathrm { e } - ( n - 2 ) I _ { n - 3 }$$

(iii) Hence find the exact value of $I _ { 8 }$.\\

\hfill \mbox{\textit{CAIE FP1 2019 Q4}}