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Ch. 7 - Logarithmic, Exponential Functions, and Hyperbolic Functions
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Not the one you use?Change textbook
Chapter 7, Problem 7.3.79j

Evaluating hyperbolic functions Evaluate each expression without using a calculator or state that the value does not exist. Simplify answers as much as possible.
j. sinh⁻¹ (e² − 1)/2e

Verified step by step guidance
1
Recall the definition of the inverse hyperbolic sine function: \(\sinh^{-1}(x) = y\) means \(\sinh(y) = x\).
Set \(y = \sinh^{-1}\left(\frac{e^{2} - 1}{2e}\right)\), so that \(\sinh(y) = \frac{e^{2} - 1}{2e}\).
Use the definition of hyperbolic sine: \(\sinh(y) = \frac{e^{y} - e^{-y}}{2}\), so write the equation as \(\frac{e^{y} - e^{-y}}{2} = \frac{e^{2} - 1}{2e}\).
Multiply both sides by 2 to clear denominators: \(e^{y} - e^{-y} = \frac{e^{2} - 1}{e}\).
Recognize that \(\frac{e^{2} - 1}{e} = e - e^{-1}\), so the equation becomes \(e^{y} - e^{-y} = e - e^{-1}\). From this, deduce that \(y = 1\) because \(e^{1} - e^{-1} = e - e^{-1}\).

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Key Concepts

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

Inverse Hyperbolic Sine Function (sinh⁻¹)

The inverse hyperbolic sine function, sinh⁻¹(x), returns the value whose hyperbolic sine is x. It can be expressed as ln(x + √(x² + 1)), allowing evaluation without a calculator by simplifying the expression inside the logarithm.
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Simplification of Algebraic Expressions

Simplifying algebraic expressions involves factoring, expanding, and reducing terms to their simplest form. This skill is essential to rewrite complex expressions like (e² − 1)/2e into a form that makes applying inverse hyperbolic functions easier.
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Properties of Exponential Functions

Exponential functions with base e have properties such as e^a * e^b = e^(a+b) and (e^a)/(e^b) = e^(a-b). Understanding these helps in manipulating expressions involving e, which is crucial for simplifying and evaluating hyperbolic function arguments.
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