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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 24

Evaluate the following limits. Use l’Hôpital’s Rule when it is convenient and applicable.
lim_x→ ∞ (4x³ - 2x² + 6) / (πx³ + 4)

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First, identify the form of the limit as x approaches infinity. The given expression is (4x³ - 2x² + 6) / (πx³ + 4). As x approaches infinity, both the numerator and the denominator approach infinity, which is an indeterminate form ∞/∞.
Since the limit is in the indeterminate form ∞/∞, we can apply l'Hôpital's Rule. This rule states that if the limit of f(x)/g(x) as x approaches a value is in the form 0/0 or ∞/∞, then it can be evaluated as the limit of f'(x)/g'(x), provided this new limit exists.
Differentiate the numerator and the denominator separately. The derivative of the numerator 4x³ - 2x² + 6 is 12x² - 4x. The derivative of the denominator πx³ + 4 is 3πx².
Now, apply l'Hôpital's Rule by taking the limit of the new expression: lim_x→∞ (12x² - 4x) / (3πx²).
Simplify the expression by dividing each term by x², the highest power of x in the denominator. This gives lim_x→∞ (12 - 4/x) / (3π). As x approaches infinity, the term 4/x approaches 0, simplifying the limit to 12 / 3π.

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