Recall the Maclaurin series of and

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

Problem

Recall the Maclaurin series of ln⁡(1+x)\ln(1+x) and sin⁡x\sin x. Consider the function Q(x)=ln⁡(1+x)−sin⁡xQ(x)=\ln(1+x)-\sin x. (a) Determine the first four nonzero terms of the Maclaurin series of Q(x)Q(x) and state the corresponding coefficients. (b) Using your series from part (a), evaluate lim⁡x→0ln⁡(1+x)−sin⁡xx3\displaystyle \lim_{x\to0}\frac{\ln(1+x)-\sin x}{x^{3}}. Provide complete justification connecting the limit to a specific series coefficient.

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