Geometric Sequences (Edexcel IAL Maths)

Spec point — 4.4

Geometric sequences

What do I need to know about geometric sequences?

• In a geometric sequence, there is a common ratio between consecutive terms in the sequence

• You need to know the n^thterm formula for a geometric sequence $u_{n}=ar^{n-1}$

  • a is the first term
  • r is the common ratio

Exam Hint If you know two terms in a geometric sequence you can find a and r using simultaneous equations.

Worked Example