# infinite geometric series formula

This article is licensed under a CC BY-NC-SA 4.0 license. 1 , the sum exits. S To use this formula, our r has to be between -1 and 1, but it cannot be 0. ∴ S∞ = ∞ ∑ i=1 ari−1 = a 1 − r (−1 < r < 1) ∴ S ∞ = ∑ i = 1 ∞ a r i − 1 = a 1 − r ( − 1 < r < 1) where. 20. 10 S 1 Varsity Tutors © 2007 - 2020 All Rights Reserved, GRE Subject Test in Mathematics Test Prep, GRE Subject Test in Physics Courses & Classes, SE Exam - Professional Licensed Engineer Structural Engineering Exam Test Prep. \begin{align*} \text{Let } x &= \text{0. As of 4/27/18. For example: Use infinite geometric series as models of real-life situations, such as the distance traveled by a bouncing ball in Example 4. 1 ( If -1 < r < 1, then the infinite geometric series. 3. This is a geometric series with $$r = \text{0.1} = \cfrac{1}{10}$$. . is the first term and = for   Instructors are independent contractors who tailor their services to each client, using their own style,   For example, 1 The general form of the infinite geometric series is The infinity symbol that placed above the sigma notation indicates that the series is infinite. a 1 + a 1 r + a 1 r 2 + a 1 r 3 + ... + a 1 r n-1. geometric sequence , we can have the sum of an infinite geometric series. − See also. 1 An infinite \begin{align*}{S}_{n}& = \cfrac{{a}(1 – {r}^{n} )}{1 – r} \\\text{If } -1 < r < 1, \quad & \text{then } r^{n} arrow 0 \text{ as } n arrow \infty \\\therefore {S}_{\infty }& = \cfrac{{a}(1 – 0 )}{1 – r} \\ & = \cfrac{{a}}{1-r} \end{align*}, The sum of an infinite geometric series is given by the formula, \[\therefore {S}_{\infty }=\sum _{i=1}^{\infty }{a}{r}^{i-1}=\cfrac{{a}}{1-r} \qquad (-1