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Ch. 10 - Infinite Sequences and Series
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077당신이 사용하는 게 아니라요?교과서 변경
10장, 문제 10.2.89

Make up an infinite series of nonzero terms whose sum is
b. −3

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Recall that an infinite series is the sum of infinitely many terms, and for the series to have a finite sum, it must be convergent.
One common type of infinite series with a known sum is a geometric series, which has the form \(\sum_{n=0}^{\infty} ar^n = \frac{a}{1-r}\), where \(|r| < 1\).
To create a series that sums to \(b - 3\), choose the first term \(a\) and common ratio \(r\) such that \(\frac{a}{1-r} = b - 3\).
For example, pick a value for \(r\) with \(|r| < 1\), then solve for \(a = (b - 3)(1 - r)\) to ensure the sum matches \(b - 3\).
Write the infinite series explicitly as \(\sum_{n=0}^{\infty} a r^n\), substituting the values of \(a\) and \(r\) you chose, which will be a series of nonzero terms summing to \(b - 3\).

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Infinite Series and Convergence

An infinite series is the sum of infinitely many terms. For the series to have a finite sum, it must converge, meaning its partial sums approach a specific value. Understanding convergence criteria is essential to construct a series that sums to a given number.
추천 영상:
06:52
Convergence of an Infinite Series

Geometric Series

A geometric series has terms that multiply by a constant ratio each time. If the absolute value of the ratio is less than one, the series converges to a sum given by a/(1 - r), where a is the first term and r is the ratio. This formula helps create series with a desired sum.
추천 영상:
06:00
Geometric Series

Constructing Series with a Given Sum

To create an infinite series summing to a specific value, choose terms that satisfy convergence and sum conditions. For example, adjusting the first term and ratio in a geometric series allows the sum to equal any real number, including negative values like −3.
추천 영상:
06:45
Intro to Series: Partial Sums