Edexcel FP1 — Question 2 7 marks

Exam BoardEdexcel
ModuleFP1 (Further Pure Mathematics 1)
Marks7
PaperDownload PDF ↗
TopicSequences and series, recurrence and convergence
TypeStandard summation formulae application
DifficultyStandard +0.3 This is a straightforward proof by induction (or algebraic manipulation) followed by a simple deduction about divisibility. Part (a) requires standard summation techniques with a given result to prove, and part (b) is a direct consequence requiring minimal additional reasoning. While it involves multiple steps, the techniques are routine for Further Maths students and the result is provided rather than requiring discovery.
Spec4.01a Mathematical induction: construct proofs8.02l Fermat's little theorem: both forms

  1. Prove that \(\sum_{r=1}^{n} (r + 1)(r - 1) = \frac{1}{6} n (n - 1)(2n + 5)\). [5]
  2. Deduce that \(n(n - 1)(2n + 5)\) is divisible by 6 for all \(n > 1\). [2]

\begin{enumerate}[label=(\alph*)]
\item Prove that $\sum_{r=1}^{n} (r + 1)(r - 1) = \frac{1}{6} n (n - 1)(2n + 5)$. [5]
\item Deduce that $n(n - 1)(2n + 5)$ is divisible by 6 for all $n > 1$. [2]
\end{enumerate}

\hfill \mbox{\textit{Edexcel FP1  Q2 [7]}}