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3.4 Sequences and Series (A-level only)

3.4 Sequences and Series (A-level only)

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Question 5

An arithmetic sequence has first term a a\,a and common difference ddd. The sum of the first 8 terms of the sequence is 198.

a.

Show that 4a+14d=994a + 14d = 994a+14d=99.

[2]
b.

Given that the sum of the first 25 terms is 300, find the sum of the first 21 terms.

[3]
c.

Sn S_n\,Sn​ is the sum of the first n n\,n terms of the sequence. Explain why the value you found in part (b) is the maximum value of SnS_nSn​.

[2]
Markscheme

3.4 Sequences and Series (A-level only) Questions

  1. A Level
  2. /Maths
  3. /3.4 Sequences and Series (A-level only)

231 exam-style questions on WJEC A Level Maths 3.4 Sequences and Series (A-level only), covering 3.4.1 Sequences and Series (A-level only), 3.4.2 Sequences and Series (A-level only), 3.4.3 Sequences and Series (A-level only), 3.4.4 Sequences and Series (A-level only), 3.4.5 Sequences and Series (A-level only), 3.4.6 Sequences and Series (A-level only), and 3.4.7 Sequences and Series (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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