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1.7 D: Sequences and series

1.7 D: Sequences and series

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Question 10

An arithmetic series has first term a a\,a and common difference ddd. The sum of the first n n\,n terms of the series is SnS_nSn​.

By writing Sn S_n\,Sn​ out both forwards and in reverse, and adding the two expressions, prove that

Sn=12n[2a+(n−1)d]S_n = \tfrac{1}{2}n\left[2a + (n - 1)d\right]Sn​=21​n[2a+(n−1)d]

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Markscheme

1.7 D: Sequences and series Questions

  1. A Level
  2. /Maths
  3. /1.7 D: Sequences and series

308 exam-style questions on AQA A Level Maths 1.7 D: Sequences and series, covering 1.7.1 Binomial expansion, 1.7.2 Types of sequence (A-level only), 1.7.3 Sigma notation (A-level only), 1.7.4 Arithmetic sequences and series (A-level only), 1.7.5 Geometric sequences and series (A-level only), and 1.7.6 Sequences and series in modelling (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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