A geometric progression is a sequencewhere every term bears a continuous ratioto its coming before term. Geometric progression is a special kind of sequence. In bespeak to gain the following term in the geometric progression, we need to multiply v afixed term well-known as the common ratio,every time, and if we desire to uncover the preceding term in the sequence, us just need to divide the term through the same usual ratio. Here is anexample the a geometric progression is 2, 4, 8, 16, 32, ...... Having actually a common ratio that 2.

You are watching: What is the difference between an arithmetic sequence and a geometric sequence

The geometric progressions can be a finite series or an limitless series. The common ratio of a geometric progression can be a an unfavorable or a confident integer. Here we candlestick learn an ext about the geometric development formulas, and the different varieties of geometric progressions.

1.Geometric development Introduction
2.Geometric progression Formula
3.Geometric development Sum Formula
4.Geometric development Examples
5.Practice concerns on Geometric Progression
6.FAQs ~ above Geometric Progression

Geometric progression Introduction

A geometric development is a special form of sequencewhere the successive terms bear a continuous ratio recognize as a typical ratio. Geometric development is additionally known together GP. The geometric succession is usually represented in type a, ar, ar2.... Whereby a is the first term and r is the common ratioof the sequence. The usual ratio deserve to have both an adverse as fine as hopeful values.To uncover the regards to a geometric series, us only require the first termand the continuous ratio.


The geometric development isof 2 types. The two species of geometric progressions are based upon the number of terms in the development series. The two species of a geometric development are the limited geometric progression and the unlimited geometric progression. The details of the two geometric progressions space as follows.

Finite geometric progression

Finite geometric development is the geometric collection that contains a finite number of terms. That is the sequence whereby the last term is defined. For example 1/2,1/4,1/8,1/16,...,1/32768 is a finite geometric collection where the critical term is 1/32768.

Infinite geometric progression

Infinite geometric development is the geometric series that includes an infinite variety of terms. The is the sequence where the critical term is no defined. For example, 3, −6, +12, −24, +... Is an infinite series where the critical term is not defined.

Geometric development Formula

The geometric development formula is provided to discover the nth term in the sequence. To discover the nth term in the geometric progression, we require the first term and also the common ratio. If the typical ratio is not known, the common ratio is calculated by finding the ratio of any kind of term by its preceding term.The formula because that the nth term of the geometric progression is:

\(a_n\) = arn-1


a is the first termr is the common ration is the number of the hatchet which we want to find.

Geometric development Sum Formula

The geometric development sum formula is used to find the sum of all the state in a geometric sequence. As we review in the over section the geometric sequenceis of 2 types, finite and infinite geometric sequences, thus the sumof your termsis also calculated by various formulas.

Finite Geometric Series

If the number of terms in a geometric succession is finite, then the amount of the geometric series is calculation by the formula:

\(S_n\) = a(1−rn)/(1−r) forr≠1, and

\(S_n\) = an because that r = 1


a is the first termr is the common ratio n is the number of the state in the series

Infinite Geometric Series

If the variety of terms in a geometric succession is infinite,an infinite geometricseries sum formula is used. In boundless series, there arise two situations depending upon the worth of r. Let us comment on the infinite series sum formula because that the 2 cases.

Case 1: When|r| a is the first termr is the usual ratio

Case 2:|r| >1

In this case, the series does not converge and also it has no sum.

Geometric development vs Arithmetic Progression

Here are a few differences in between geometric progression and arithmetic progression shown in the table below:

Geometric ProgressionArithmetic Progression
GP has actually the same usual ratio throughout.AP does no have usual ratio.
GP does no have common difference.AP has actually the same typical difference throughout.
A new term is the product the the previous term and also the usual ratioA new term is the enhancement of the vault term and also the usual difference.
An unlimited geometric succession is one of two people divergent or convergent.An limitless arithmetic sequence is divergent.
The variation of the terms is non-linear.The sports of the terms is linear.

Important notes on Geometric Progression

In a geometric progression, each succeeding term is acquired by multiply the typical ratio come its coming before term.

The formula for the nthterm the a geometric development whose first term is aand common ratio is \(r\) is: \(a_n=ar^n-1\)

The sum of n state in GP whose an initial term is aand the usual ratio is rcan be calculated usingthe formula: \(S_n=\dfraca(1-r^n)1-r\)

The sum of unlimited GP formula is provided as: \(S_n=\dfraca1-r\) wherein |r|

Related subject on Geometric Progression

Check the end these interesting posts related come geometric progression:


Observe that each square is fifty percent of the dimension of the square alongside it. Which succession does this sample represent?


Let's compose the geometric development seriesrepresented in the figure.

1, 1/2, 1/4, 1/8 ...

Every successive term is acquired by splitting its coming before term by 2

The sequence exhibits a typical ratio the 1/2.

Answer:The pattern represents the geometric progression.

Question 2: In a particular culture, the counting of bacteria it s okay doubled ~ every hour. There were 3 bacteria in the culture initially. What would be the total count of bacteria at the finish of the 6th hour?


Here, the number of bacteria forms a geometric progression where the an initial term ais 3 and also the common ratio ris 2.

So, the total number of bacteria in ~ the finish of the sixth hour will certainly be the sum of the first 6 terms of this progression offered by \(S_6\).

See more: How To Remove Ignition Lock Cylinder Without Key Chevy Truck Without The Key?

\(S_6\) = 3(26−1)/(2−1)




Answer:So, the complete count that bacteria at the end of the sixth hour will be 189.

Example 3: uncover the following sum the the regards to this infinite geometric progression: