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Ch. 8 - Techniques of Integration
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Non è quello che usi tu?Cambia libro di testo
Capitolo 8, Problema 8.PE.53

Evaluate the improper integrals in Exercises 53–62.
∫ from 0 to 3 of (1 / √(9 − x²)) dx

Guida verificata passo dopo passo
1
Recognize that the integral \( \int_0^3 \frac{1}{\sqrt{9 - x^2}} \, dx \) is an improper integral because the integrand involves a square root in the denominator that becomes zero at the upper limit \( x = 3 \). This means the function approaches infinity there, so we need to treat the integral as a limit.
Rewrite the integral as a limit: \( \lim_{t \to 3^-} \int_0^t \frac{1}{\sqrt{9 - x^2}} \, dx \). This allows us to evaluate the integral over \( [0, t] \) where \( t < 3 \) and then take the limit as \( t \) approaches 3 from the left.
Recall the antiderivative formula for \( \int \frac{1}{\sqrt{a^2 - x^2}} \, dx = \arcsin\left( \frac{x}{a} \right) + C \). In this problem, \( a = 3 \), so the antiderivative is \( \arcsin\left( \frac{x}{3} \right) + C \).
Evaluate the definite integral from 0 to \( t \) using the antiderivative: \( \int_0^t \frac{1}{\sqrt{9 - x^2}} \, dx = \arcsin\left( \frac{t}{3} \right) - \arcsin(0) \). Since \( \arcsin(0) = 0 \), this simplifies to \( \arcsin\left( \frac{t}{3} \right) \).
Finally, take the limit as \( t \to 3^- \): \( \lim_{t \to 3^-} \arcsin\left( \frac{t}{3} \right) \). This will give the value of the improper integral.

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