Chapter 7: Problem 60
(a) Make an appropriate \(u\) -substitution of the form \(u=x^{1 / n}\) or \(u=(x+a)^{1 / n}\), and then evaluate the integral. (b) If you have a CAS, use it to evaluate the integral, and then confirm that the result is equivalent to the one that you found in part (a). $$ \int \frac{\sqrt{x}}{x+1} d x $$
Short Answer
Step by step solution
Identify the Substitution
Perform the Substitution
Simplify the Integral
Integrate Each Part
Back-Substitute the Variable
Confirm with CAS
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding u-substitution
- Select the substitution: Choose a part of the integrand to become new variable \( u \). For example, in the integral \( \int \frac{\sqrt{x}}{x+1} \, dx \), \( u = \sqrt{x} \).
- Express \( x \) in terms of \( u \): This involves solving for \( x \) from the chosen \( u \). Here, it becomes \( x = u^2 \).
- Find \( dx \): Differentiate \( x = u^2 \) to get \( dx = 2u \, du \).
- Substitute in the integral: Replace \( x \), \( \sqrt{x} \), and \( dx \) in the original integral with the expressions in terms of \( u \). This changes the integral to \( 2 \int \frac{u^2}{u^2 + 1} \, du \).
The Role and Calculation of Antiderivatives
- Simplify the integral expression: The given example involves the substitution-integrand \( 2 \int \left(1 - \frac{1}{u^2 + 1}\right) \, du \). Split the integral into simpler parts: \( 2 \int 1 \, du - 2 \int \frac{1}{u^2 + 1} \, du \).
- Integrate each part:
- Constant terms: \( \int 1 \, du = u \)
- Arctangent function: \( \int \frac{1}{u^2 + 1} \, du = \tan^{-1}(u) \)
- Combine the results: Bring these results together to form the complete antiderivative: \( 2 ( u - \tan^{-1}(u) ) + C \).
Exploring Computer Algebra Systems in Integral Calculus
- Verification: After manually calculating the antiderivative using techniques like u-substitution, the result can be verified using a CAS. In our example, it confirmed that the antiderivative \( 2 \left( \sqrt{x} - \tan^{-1}(\sqrt{x}) \right) + C \) was correct.
- Speed and accuracy: CAS offers a quick and accurate solution, reducing human error that could occur in manual calculations.
- Complex problems: Able to handle more complex integrals that may be challenging to solve by hand, saving time in educational and professional settings.