Sum of Geometric Series

What is geometric series?

A geometric series is a sequence of numbers in which ratio of each succeeding term to the preceding term remains the same. This ratio is called common ratio of the GP.

What is the formula for sum of geometric series?

The formula to find sum of a geometric series is given as, S = a × (rn – 1)/(r – 1), where S is the sum of the series, a is the first term, r is the common ratio, and n is the number of terms.

When can we use the formula for the sum of an infinite geometric series?

The formula for the sum of an infinite geometric series can be used when the absolute value of the common ratio ∣r∣ is less than 1. In this case, the sum is given by:

S = a/(1 – r)

What happens if the common ratio r is greater than or equal to 1?

If the absolute value of the common ratio ∣r∣ is greater than or equal to 1, the series diverges, meaning it grows without bound as the number of terms increases.

What are some applications of geometric series in real life?

Geometric series have various applications in fields such as finance (e.g., compound interest calculations), population growth models, computer algorithms, and physics (e.g., modeling radioactive decay).



How to Find the Sum of Geometric Series

A geometric series is a sequence of numbers where each term after the first term is found by multiplying the previous term by a fixed, non-zero number called the common ratio. In a geometric series, if the absolute value of the common ratio (∣r∣) is less than 1, the series converges to a finite value. Otherwise, it diverges (grows without bound). Let’s know more about sum of Geometric Series formula, derivation and examples in detail below.

How to Find the Sum of Geometric Series

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Geometric Series

A geometric series is a sequence of numbers in which each term except the first is obtained by multiplying the preceding term with a constant value known as common ratio. The common ratio can be less than 1, equal to 1 or greater than 1. A geometric series is also known as a geometric progression(GP). Mathematically, it is represented as follows:...

Examples of Geometric Series

Some examples of geometric series are:...

Geometric Sum Formula

We have derived the expression for sum of a geometric series. Below is the formula for different common Ratio in a Geometric Series....

Derivation of Geometric Sum Formula

The sum of a geometric series up to a finite number of terms is derived as follows. Let us call Sn as the sum of a geometric series up to n terms. Then, we have,...

Sum of an Infinite Geometric Series

The sum of a geometric series having common ratio less than 1 up to infinite terms can be found. Let us derive the expression for sum as follows. We have, sum of a geometric series up to n terms given by,...

Solved Examples on Sum of Geometric Series

Example 1: Find the sum of first 5 terms of a geometric series having first term as 1 and common ratio as 2....

Practice Problems on Sum of Geometric Series

Problem 1: Find sum of the series: 4, 12, 36, 108, . . . up to 6 terms....

Sum of Geometric Series – FAQs

What is geometric series?...

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