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Sequences and Series

Sequences and Series

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Question 51

A sequence u1,u2,u3,… u_1, u_2, u_3, \dots\,u1​,u2​,u3​,… is defined by

u1=3un+1=un+c,n≥1 \begin{aligned}u_1 &= 3 \\u_{n+1} &= u_n + c, \quad n \geq 1\end{aligned} u1​un+1​​=3=un​+c,n≥1​

Given u5=21u_5 = 21u5​=21

a.

Find the value of ccc.

[3]
b.

Find an expression for un u_n\,un​ in terms of nnn.

[2]
Markscheme

Sequences and Series Questions

  1. A Level
  2. /Maths
  3. /Sequences and Series

178 exam-style questions on Edexcel A Level Maths Sequences and Series, covering 3.1 Arithmetic Sequences, 3.2 Arithmetic Series, 3.3 Geometric Sequences, 3.4 Geometric Series, 3.5 Sum to Infinity, 3.6 Sigma Notation, 3.7 Recurrence Relations, and 3.8 Modelling with Series. Each one has a worked solution and a mark scheme showing where the marks go.

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