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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 7.5.35

Use l’Hôpital’s rule to find the limits in Exercises 7–52.
35. lim (x → 0⁺) ln(x² + 2x) / ln x

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First, identify the form of the limit as \( x \to 0^+ \). Substitute \( x = 0^+ \) into the expression \( \frac{\ln(x^2 + 2x)}{\ln x} \) to check if it results in an indeterminate form like \( \frac{0}{0} \) or \( \frac{\infty}{\infty} \).
Since \( \ln x \) approaches \( -\infty \) as \( x \to 0^+ \), and \( \ln(x^2 + 2x) \) also approaches \( -\infty \) because \( x^2 + 2x \to 0^+ \), the limit is of the form \( \frac{-\infty}{-\infty} \), which is an indeterminate form suitable for l'Hôpital's Rule.
Apply l'Hôpital's Rule by differentiating the numerator and denominator separately with respect to \( x \). The derivative of the numerator is \( \frac{d}{dx} \ln(x^2 + 2x) = \frac{2x + 2}{x^2 + 2x} \). The derivative of the denominator is \( \frac{d}{dx} \ln x = \frac{1}{x} \).
Rewrite the limit using these derivatives: \[ \lim_{x \to 0^+} \frac{\frac{2x + 2}{x^2 + 2x}}{\frac{1}{x}} = \lim_{x \to 0^+} \frac{2x + 2}{x^2 + 2x} \times x \]. Simplify the expression inside the limit before evaluating.
After simplification, evaluate the limit as \( x \to 0^+ \) by substituting \( x = 0^+ \) into the simplified expression to find the limit.

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