The series converges

MATHEMATICS · Multi-part · AP · Calculus BC · Infinite Sequences and Series · Infinite Sequences and Series

Problem

The series ∑n=1∞(−1)n+11n3\displaystyle \sum_{n=1}^{\infty}(-1)^{n+1}\frac{1}{n^{3}} converges. Use the following tasks to approximate its sum to within 0.00010.0001. (a) Determine the least positive integer NN such that the magnitude of the error made by using SNS_{N} to approximate the sum is less than 0.00010.0001. Show analytic reasoning that leads to your value of NN. Do not evaluate any partial sums in this part. (b) Compute SNS_{N} found in part (a) to six decimal places. (c) State how many correct decimal digits your approximation from part (b) guarantees for the exact sum of the series. Explain your reasoning.

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