Skip to main content
Ch. 7 - Transcendental Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Not the one you use?Change textbook
Chapter 7, Problem 7.7.82c

82. Use the definitions of the hyperbolic functions to find each of the following limits.
c. lim(x→∞) sinh x

Verified step by step guidance
1
Recall the definition of the hyperbolic sine function: \(\sinh x = \frac{e^{x} - e^{-x}}{2}\).
Rewrite the limit using this definition: \(\lim_{x \to \infty} \sinh x = \lim_{x \to \infty} \frac{e^{x} - e^{-x}}{2}\).
Analyze the behavior of each term inside the limit as \(x\) approaches infinity: \(e^{x}\) grows without bound, while \(e^{-x}\) approaches zero.
Since \(e^{x}\) dominates \(e^{-x}\) for large \(x\), the expression behaves like \(\frac{e^{x}}{2}\) as \(x \to \infty\).
Conclude that the limit depends on the growth of \(e^{x}\), which increases without bound, so the limit tends toward infinity.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
3m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Definition of Hyperbolic Sine Function

The hyperbolic sine function, sinh x, is defined as (e^x - e^(-x)) / 2. Understanding this definition is crucial because it expresses sinh x in terms of exponential functions, which simplifies the evaluation of limits involving sinh x.
Recommended video:
05:43
Definition of the Definite Integral

Behavior of Exponential Functions at Infinity

As x approaches infinity, e^x grows without bound, while e^(-x) approaches zero. Recognizing this behavior helps in simplifying expressions like sinh x by focusing on dominant terms when evaluating limits at infinity.
Recommended video:
5:46
Graphs of Exponential Functions

Limit Evaluation Techniques

Evaluating limits often involves identifying dominant terms and applying limit laws. For sinh x as x approaches infinity, this means simplifying the expression using the exponential growth rates to determine the limit accurately.
Recommended video:
05:50
One-Sided Limits