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freeCodeCamp/guide/english/mathematics/geometric-series/index.md
Aman Kumar 519f08da03 Introduced Geometric progression (#21517)
* Introduced Geometric progression

* Fixed some typos and added geometric mean

* fixed some more typos

* Added Design Patterns book

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2018-11-10 21:35:24 +00:00

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Geometric Series

Geometric Series

A geometric progression is a sequence of numbers, whose first term is non zero and each term is obtained by multiplying its proceding term by a constant quantity. This constant quantity is called common ratio of the GP.

The sum of this progression is called geometric series.

We can say if a1,a2,a3,....,an are in GP then

is known as common ratio of GP.

if a is the first term then GP can be written as

example of a GP : 2,4,8,16,....

The nth term of GP (Also known as General term)

Let a be the first term, r be the common ratio and l be the last term of a GP, then nth term is given by

where

The sum of n terms of a GP

Let a be the first term, r be the common ratio and l be the last term of a GP, then sum of n terms is given by:

and is not defined for r=1

Geometric Mean

if we insert geometric mean between two numbers and , then

Geometric mean =