A mathematician is reviewing fundamental vocabulary related to infinite series

MATHEMATICS · Subjective · AP · Calculus BC · Infinite Sequences and Series · Infinite Sequences and Series

Problem

A mathematician is reviewing fundamental vocabulary related to infinite series. (a) State the definitions of “absolute convergence” and “conditional convergence” for an infinite series ∑n=1∞an\sum_{n=1}^{\infty} a_n. (b) Consider the series ∑n=1∞(−1)n+1n2\displaystyle \sum_{n=1}^{\infty} \dfrac{(-1)^{n+1}}{n^2}. Indicate whether this series is absolutely convergent, conditionally convergent, or divergent, and provide a brief justification. (c) Give the precise statement that relates the convergence behavior of a rearranged series to the type of convergence (absolute or conditional) of the original series. In one or two sentences, distinguish how this property differs for absolutely versus conditionally convergent series.

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