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Ch. 8 - Integration Techniques
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Non è quello che usi tu?Cambia libro di testo
Capitolo 8, Problema 8.6.13

7–84. Evaluate the following integrals.
13. ∫ [1 / (eˣ √(1 – e²ˣ))] dx

Guida verificata passo dopo passo
1
Step 1: Recognize that the integral involves a composite function. The term √(1 - e²ˣ) suggests a substitution might simplify the expression. Let u = eˣ, which implies du = eˣ dx.
Step 2: Rewrite the integral in terms of u. Substituting u = eˣ, dx = du / u. The integral becomes ∫ [1 / (u √(1 - u²))] * (du / u). Simplify the expression to ∫ [1 / (u² √(1 - u²))] du.
Step 3: Notice that the integral now resembles a standard form involving √(1 - u²). This suggests a trigonometric substitution. Let u = sin(θ), which implies du = cos(θ) dθ and √(1 - u²) = √(1 - sin²(θ)) = cos(θ).
Step 4: Substitute u = sin(θ) into the integral. The expression becomes ∫ [1 / (sin²(θ) * cos(θ))] * cos(θ) dθ. Simplify to ∫ [1 / sin²(θ)] dθ.
Step 5: Use the identity 1 / sin²(θ) = csc²(θ). The integral becomes ∫ csc²(θ) dθ, which is a standard integral. The result of this integral is -cot(θ) + C. Finally, back-substitute θ = arcsin(u) and u = eˣ to express the solution in terms of x.

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Integration is a fundamental concept in calculus that involves finding the accumulated area under a curve represented by a function. It is the reverse process of differentiation and can be used to calculate quantities such as areas, volumes, and total accumulated change. Understanding the techniques of integration, such as substitution and integration by parts, is essential for evaluating integrals.
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The substitution method is a technique used in integration to simplify the process by changing the variable of integration. By substituting a part of the integrand with a new variable, the integral can often be transformed into a more manageable form. This method is particularly useful when dealing with composite functions or when the integrand contains a function and its derivative.
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