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Ch. 8 - Sequences, Induction, and Probability
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514당신이 사용하는 게 아니라요?교과서 변경
9장, 문제 89

Exercises 88–90 will help you prepare for the material covered in the next section. Consider the sequence whose nth term is an = (3)5n Find a2/a3, a1/a2, a4/a3 and a5/a4 What do you observe?

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Identify the general term of the sequence given by an = 3 imes 5^n. This means each term is 3 times 5 raised to the power of n.
Write expressions for the specific terms needed: a_1 = 3 imes 5^1, a_2 = 3 imes 5^2, a_3 = 3 imes 5^3, a_4 = 3 imes 5^4, and a_5 = 3 imes 5^5.
Calculate each ratio by dividing the corresponding terms: \(\frac{a_2}{a_3}\) = \(\frac{3 imes 5^2}{3 imes 5^3}\), \(\frac{a_1}{a_2}\) = \(\frac{3 imes 5^1}{3 imes 5^2}\), \(\frac{a_4}{a_3}\) = \(\frac{3 imes 5^4}{3 imes 5^3}\), and \(\frac{a_5}{a_4}\) = \(\frac{3 imes 5^5}{3 imes 5^4}\).
Simplify each ratio by canceling the common factor 3 and applying the properties of exponents: \(\frac{5^m}{5^n}\) = 5^{m-n}. For example, \(\frac{a_2}{a_3}\) = 5^{2-3} = 5^{-1}.
Observe the simplified ratios to identify any pattern or relationship, such as whether the ratios are constant or follow a specific rule related to the powers of 5.

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주요 개념

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

Sequences and Terms

A sequence is an ordered list of numbers defined by a specific formula for its nth term. Understanding how to find individual terms using the given formula an = 3 * 5^n is essential to evaluate and compare terms in the sequence.
추천 영상:
8:22
Introduction to Sequences

Ratio of Consecutive Terms

The ratio of consecutive terms in a sequence is found by dividing one term by the next or previous term. This concept helps identify patterns such as constant ratios, which indicate geometric sequences.
추천 영상:
4:18
Geometric Sequences - Recursive Formula

Geometric Sequences

A geometric sequence is one where each term is found by multiplying the previous term by a fixed constant called the common ratio. Recognizing this helps explain why ratios like a2/a3 or a5/a4 are constant in sequences defined by exponential expressions.
추천 영상:
4:18
Geometric Sequences - Recursive Formula