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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 7.1.84

84. Find lim(x→∞) (√(x² + 1) - √x).

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Identify the limit expression: \(\lim_{x \to \infty} \left( \sqrt{x^{2} + 1} - \sqrt{x} \right)\).
Recognize that as \(x\) approaches infinity, both \(\sqrt{x^{2} + 1}\) and \(\sqrt{x}\) grow large, so direct substitution leads to an indeterminate form of type \(\infty - \infty\).
To resolve this, multiply and divide the expression by the conjugate of the difference to rationalize it: multiply by \(\frac{\sqrt{x^{2} + 1} + \sqrt{x}}{\sqrt{x^{2} + 1} + \sqrt{x}}\).
Simplify the numerator using the difference of squares formula: \(\left( \sqrt{x^{2} + 1} - \sqrt{x} \right) \left( \sqrt{x^{2} + 1} + \sqrt{x} \right) = (x^{2} + 1) - x\).
Rewrite the limit as \(\lim_{x \to \infty} \frac{(x^{2} + 1) - x}{\sqrt{x^{2} + 1} + \sqrt{x}}\) and then simplify the numerator and denominator separately to analyze the behavior as \(x\) approaches infinity.

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