CIE IGCSE Maths

Revision Notes

2.10.4 Sequences - Identifying

What are sequences?

  • A sequence is an order set of (usually) numbers
  • Make sure you are familiar with the basics and notation used with sequences

 

SeqId Notes fig1, downloadable IGCSE & GCSE Maths revision notes

How do I identify a sequence?

  • Is it obvious?
  • Does it tell you in the question?
  • Is there is a number that you multiply to get from one term to the next?
    • If so then it is a geometric sequence
  • Next, look at the differences between the terms
    If 1st differences are constant – it is a linear sequence
    If 2nd differences are constant – it is a quadratic sequence

SeqId Notes fig2, downloadable IGCSE & GCSE Maths revision notes

  • Special cases to be aware of:
  • If the differences repeat the original sequence
    • It is a geometric sequence with common ratio 2
  • Fibonacci sequences also have differences that repeat the original sequence
    • However questions usually indicate if a Fibonacci sequence is involved

SeqId Notes fig3, downloadable IGCSE & GCSE Maths revision notes

Worked Example

SeqId Example fig1 sola, downloadable IGCSE & GCSE Maths revision notes

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