Edexcel FP2 — Question 34 11 marks

Exam BoardEdexcel
ModuleFP2 (Further Pure Mathematics 2)
Marks11
PaperDownload PDF ↗
TopicTaylor series
TypeDirect multiplication of series
DifficultyChallenging +1.2 This is a standard Further Maths FP2 question combining proof by induction with Taylor series. Part (a) requires a methodical induction proof with trigonometric manipulation but follows a predictable structure. Part (b) is routine application of the result from (a) to find Maclaurin coefficients. While requiring multiple techniques and careful algebra, it's a textbook-style question without novel insight, making it moderately harder than average A-level but standard for Further Maths.
Spec4.01b Complex proofs: conjecture and demanding proofs4.08a Maclaurin series: find series for function

  1. Prove by induction that $$\frac{d^n}{dx^n}(e^x \cos x) = 2^{\frac{1}{2}n} e^x \cos\left(x + \frac{1}{4}n\pi\right), \quad n \geq 1.$$ [8]
  2. Find the Maclaurin series expansion of \(e^x \cos x\), in ascending powers of \(x\), up to and including the term in \(x^4\). [3]

\begin{enumerate}[label=(\alph*)]
\item Prove by induction that
$$\frac{d^n}{dx^n}(e^x \cos x) = 2^{\frac{1}{2}n} e^x \cos\left(x + \frac{1}{4}n\pi\right), \quad n \geq 1.$$ [8]

\item Find the Maclaurin series expansion of $e^x \cos x$, in ascending powers of $x$, up to and including the term in $x^4$. [3]
\end{enumerate}

\hfill \mbox{\textit{Edexcel FP2  Q34 [11]}}