Geometric Progressions (Cambridge International AS Mathematics)

Geometric Sequences

Geometric progressions

What is a geometric progression?

• In a geometric progression(also called geometric sequence) there is a common ratio between consecutive terms in the sequence

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

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

Exam Hint

• The formula is given in the formula booklet
• If you know two terms in a geometric sequence you can find a and r using simultaneous equations.

Worked Example