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Ch. 4 - Applications of the Derivative
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Non è quello che usi tu?Cambia libro di testo
Capitolo 4, Problema 4.7.73

17–83. Limits Evaluate the following limits. Use l’Hôpital’s Rule when it is convenient and applicable.


lim_x→∞ x³ (1/x - sin 1/x)

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First, rewrite the expression inside the limit: x³ (1/x - sin(1/x)) = x³ * (1/x) - x³ * sin(1/x). This simplifies to x² - x³ * sin(1/x).
Consider the limit of each term separately as x approaches infinity. Start with the first term: lim_{x→∞} x². As x approaches infinity, x² also approaches infinity.
Now, consider the second term: lim_{x→∞} x³ * sin(1/x). As x approaches infinity, 1/x approaches 0, and sin(1/x) approaches sin(0), which is 0. Therefore, the expression becomes x³ * 0, which is 0.
Combine the results of the two limits: The first term approaches infinity, and the second term approaches 0. Therefore, the overall limit is dominated by the first term.
Conclude that the limit of the original expression as x approaches infinity is infinity, since the x² term grows without bound while the x³ * sin(1/x) term approaches 0.

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