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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 153

A sequence of daily depth changes in a reservoir, x1,x2,x3,…x_1, x_2, x_3, \dotsx1​,x2​,x3​,…, is defined by the recurrence relation

xn+1=2(xn+2)2−10 x_{n+1} = 2(x_n + 2)^2 - 10 xn+1​=2(xn​+2)2−10 x1=k−2 x_1 = k - 2 x1​=k−2

where kkk is a constant.

a.

Find an expression for x2x_2x2​ in terms of kkk, giving your answer in simplest form.

[2]
b.

Given that ∑n=13xn=k+22\sum_{n=1}^{3} x_n = k + 22∑n=13​xn​=k+22

find the possible values of x2x_2x2​.

[5]
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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