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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 7.5.63

Indeterminate Powers and Products
Find the limits in Exercises 53–68.
63. lim (x → ∞) ((x + 2)/(x - 1))^x

Guida verificata passo dopo passo
1
Identify the limit expression: \(\lim_{x \to \infty} \left( \frac{x + 2}{x - 1} \right)^x\).
Rewrite the base inside the parentheses to express it in a form that approaches 1 as \(x\) approaches infinity. For example, write \(\frac{x + 2}{x - 1} = \frac{x - 1 + 3}{x - 1} = 1 + \frac{3}{x - 1}\).
Recognize that the limit has the indeterminate form \(1^\infty\), which suggests using the exponential and logarithm transformation: rewrite the limit as \(\lim_{x \to \infty} e^{x \ln \left(1 + \frac{3}{x - 1} \right)}\).
Focus on evaluating the exponent limit: \(\lim_{x \to \infty} x \ln \left(1 + \frac{3}{x - 1} \right)\). Use the fact that \(\ln(1 + y) \approx y\) for small \(y\) to simplify the expression inside the limit.
Calculate the simplified limit of the exponent, then substitute back into the exponential function to find the overall limit.

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Limits at infinity describe the behavior of a function as the input variable grows without bound. Understanding how expressions behave as x approaches infinity helps determine the end behavior of functions, which is essential for evaluating limits like ((x + 2)/(x - 1))^x as x → ∞.
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