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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 10.3.49

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


49.0.037̅ = 0.037037…

검증된 단계별 안내
1
Identify the repeating decimal part. Here, the repeating block is "037", which repeats indefinitely after the decimal point.
Express the decimal as a sum of its non-repeating part plus the repeating part written as an infinite geometric series. Since the repeating block "037" starts immediately after the decimal, write it as: \(0.037 + 0.000037 + 0.000000037 + \cdots\).
Rewrite the repeating part as a geometric series with the first term \(a = 0.037\) and common ratio \(r = 10^{-3}\) (because the repeating block has 3 digits, so each term is shifted by 3 decimal places). 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.
Combine the sum of the geometric series with any non-repeating part (if any) and simplify the expression to write the decimal as a fraction (ratio of two integers).

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
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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. For example, 0.037037… has the block '037' repeating endlessly. Understanding this pattern is essential to express the decimal as a series or fraction.
추천 영상:
08:23
Repeated Integration by Parts

Geometric Series

A geometric series is a sum of terms where each term is found by multiplying the previous term by a constant ratio. Repeating decimals can be represented as infinite geometric series by identifying the repeating block as the first term and the power of 10 as the common ratio.
추천 영상:
06:00
Geometric Series

Conversion of Geometric Series to Fraction

An infinite geometric series with first term a and common ratio r (|r|<1) sums to a/(1-r). Using this formula, the repeating decimal's geometric series can be converted into a fraction, expressing the decimal as a ratio of two integers.
추천 영상:
06:00
Geometric Series