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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 7.8.3e

3. Which of the following functions grow faster than x² as x→∞? Which grow at the same rate as x²? Which grow slower?
e. x ln(x)

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1
Recall that to compare growth rates of functions as \(x \to \infty\), we often use limits of their ratios. Specifically, for two functions \(f(x)\) and \(g(x)\), we consider \(\lim_{x \to \infty} \frac{f(x)}{g(x)}\).
Here, we want to compare \(f(x) = x \ln(x)\) with \(g(x) = x^{2}\). So, set up the limit: \(\lim_{x \to \infty} \frac{x \ln(x)}{x^{2}}\).
Simplify the expression inside the limit: \(\frac{x \ln(x)}{x^{2}} = \frac{\ln(x)}{x}\). Now, analyze the behavior of \(\frac{\ln(x)}{x}\) as \(x \to \infty\).
Since \(\ln(x)\) grows slower than any positive power of \(x\), the limit \(\lim_{x \to \infty} \frac{\ln(x)}{x} = 0\). This means \(x \ln(x)\) grows slower than \(x^{2}\) as \(x \to \infty\).
Therefore, \(x \ln(x)\) grows slower than \(x^{2}\) as \(x\) approaches infinity.

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