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Ch. 7 - Transcendental Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Non è quello che usi tu?Cambia libro di testo
Capitolo 7, Problema 7.7.82i

82. Use the definitions of the hyperbolic functions to find each of the following limits.
i. lim(x→-∞) csch x

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Recall the definition of the hyperbolic cosecant function: \(\text{csch}\,x = \frac{1}{\sinh x}\).
Recall the definition of the hyperbolic sine function: \(\sinh x = \frac{e^{x} - e^{-x}}{2}\).
Analyze the behavior of \(\sinh x\) as \(x \to -\infty\). Since \(e^{x} \to 0\) and \(e^{-x} \to \infty\) as \(x \to -\infty\), determine the dominant term in \(\sinh x\).
Use the dominant term to approximate \(\sinh x\) for very large negative \(x\), then find the corresponding behavior of \(\text{csch}\,x = \frac{1}{\sinh x}\).
Conclude the limit \(\lim_{x \to -\infty} \text{csch}\,x\) based on the sign and magnitude of the approximation.

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