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Answers for “当给出部分和的公式时,如何判断无穷级数是收敛还是发散?”

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To determine if an infinite series converges or diverges when given an explicit formula for its nn-th partial sum SnS_n, evaluate the limit lim⁡n→∞Sn\lim_{n \to \infty} S_n. If this limit exists and is a finite value, the series converges to that value; if the limit is infinite or does not exist, the series diverges.

Conditions: You are given an explicit algebraic formula for the nn-th partial sum, SnS_n.; The limit is taken as n→∞n \to \infty.

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An infinite series SS is defined as the limit of its partial sums SnS_n as n→∞n \to \infty. For the series to converge, this limit must be a finite value. If lim⁡n→∞Sn=∞\lim_{n\to\infty} S_n = \infty, the sum grows without bound and does not approach a finite number, so the series diverges.

Conditions: The series is represented as S=lim⁡n→∞SnS = \lim_{n\to\infty} S_n.; The limit of the partial sums SnS_n is evaluated as n→∞n \to \infty.

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When the degree of the numerator is strictly greater than the degree of the denominator in a rational function, the function grows without bound as the variable approaches infinity. Consequently, the limit is infinity.

Conditions: The function is a quotient of two polynomials.; The degree of the numerator is greater than the degree of the denominator.; The variable approaches infinity.

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The partial sum SnS_n is the finite sum of the first nn terms, whereas the infinite series SS is defined as the limit of SnS_n as n→∞n \to \infty. While SnS_n forms a sequence of values, SS represents the single limiting value (or divergence) that this sequence approaches.

Conditions: SnS_n denotes the sum of the first nn terms.; SS denotes the infinite series ∑n=1∞an\sum_{n=1}^{\infty} a_n.; The limit is taken as n→∞n \to \infty.