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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.R.81

60–81. Limits Evaluate the following limits. Use l’Hôpital’s Rule when needed. 
lim_x→1 ( x- 1)^sinπx

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First, recognize that the limit is in an indeterminate form of 0^0 as x approaches 1. This suggests that we might need to use a logarithmic transformation to simplify the expression.
Take the natural logarithm of the expression: ln((x - 1)^sin(πx)) = sin(πx) * ln(x - 1). This allows us to transform the power into a product, which is easier to handle.
Now, evaluate the limit of the transformed expression: lim_(x→1) sin(πx) * ln(x - 1). Notice that as x approaches 1, sin(πx) approaches 0 and ln(x - 1) approaches -∞, creating an indeterminate form of 0 * -∞.
To resolve this, rewrite the expression as a quotient: lim_(x→1) (sin(πx)) / (1/ln(x - 1)). This is now in the form 0/0, which is suitable for l'Hôpital's Rule.
Apply l'Hôpital's Rule by differentiating the numerator and the denominator: differentiate sin(πx) with respect to x to get πcos(πx), and differentiate 1/ln(x - 1) with respect to x using the chain rule. Evaluate the new limit as x approaches 1.

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