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Ch. 10 - Sequences and Infinite Series
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243당신이 사용하는 게 아니라요?교과서 변경
10장, 문제 10.3.53

46–53. Decimal expansions
Write each repeating decimal first as a geometric series and then as a fraction (a ratio of two integers).
53.0.00952̅ = 0.00952952…

검증된 단계별 안내
1
Identify the repeating decimal part. Here, the decimal is 0.00952\(\overline{952}\), meaning the digits '952' repeat indefinitely starting after '0.0095'.
Express the decimal as the sum of the non-repeating part and the repeating part. The non-repeating part is 0.0095, and the repeating part starts at the thousandths place with '952' repeating.
Write the repeating part as a geometric series. The first term \( a \) corresponds to 0.000952, and the common ratio \( r \) is \( 10^{-3} \) because the block '952' repeats every 3 decimal places. So the series is \( a + ar + ar^2 + \cdots \).
Use the formula for the sum of an infinite geometric series \( S = \frac{a}{1 - r} \) to find the sum of the repeating part.
Add the non-repeating part to the sum of the repeating part, then simplify the resulting expression to write the entire decimal as a fraction \( \frac{p}{q} \) where \( p \) and \( q \) are integers.

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주요 개념

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

Repeating Decimals

A repeating decimal is a decimal number in which a sequence of digits repeats infinitely. Understanding how to identify the repeating part is essential for converting the decimal into a fraction or a series. For example, in 0.00952̅, the digits '952' repeat indefinitely.
추천 영상:
08:23
Repeated Integration by Parts

Geometric Series Representation

A repeating decimal can be expressed as an infinite geometric series where each term represents the repeating block shifted by powers of 1/10. This series has a first term and a common ratio less than 1, allowing the sum to be calculated using the geometric series formula.
추천 영상:
06:00
Geometric Series

Conversion of Geometric Series to Fraction

The sum of an infinite geometric series with first term a and common ratio r (|r|<1) is a/(1-r). Applying this to the series representing the repeating decimal allows conversion from decimal form to a fraction, expressing the decimal as a ratio of two integers.
추천 영상:
06:00
Geometric Series