Can You Solve This Advanced Definite Integral Using Residue Theorem?

In summary, to solve a definite integral, you need to identify the limits of integration and the function being integrated, and then apply techniques such as substitution, integration by parts, or trigonometric identities. A definite integral has specific limits and yields a numerical value, while an indefinite integral has no limits and represents a family of functions. Calculators can be used to solve definite integrals, but it is important to understand the underlying concepts. You can check the correctness of a solution by taking the derivative and evaluating it at the limits of integration. Definite integrals have real-world applications in physics, engineering, and economics for calculating areas, volumes, and work done by a force.
  • #1
sbhatnagar
87
0
This is classic one. Prove that

$$ \int_0^\infty \frac{dx}{\left\{x^4+(1+2\sqrt{2})x^2+1 \right\}\left\{x^{100}-x^{99}+x^{98}-\cdots +1\right\}}=\frac{\pi}{2(1+\sqrt{2})}$$
 
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  • #2
Residue theorem cound be applicable. The integrand is
[tex] [\ (x-\alpha i)(x+\alpha i)(x-\beta i)(x+\beta i)\prod_{j=1}^{100}(x+e^{\pi i (\frac{2j}{101})})\ ]^{-1} [/tex]
where for ##0< \alpha < \beta ## , ##-\alpha^2## and ##-\beta^2## are solutions of quadratic equation,
[tex]y^2+(1+2\sqrt{2})y+1=0[/tex]
But I have not found an appropriate contour. 
 
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Likes Greg Bernhardt

1. How do I approach solving a definite integral?

To solve a definite integral, you must first identify the limits of integration and the function being integrated. Then, you can use various techniques such as substitution, integration by parts, or trigonometric identities to simplify the integral and evaluate it.

2. What is the difference between a definite and indefinite integral?

A definite integral has specific limits of integration and yields a numerical value, while an indefinite integral has no limits and represents a family of functions.

3. Can I use a calculator to solve a definite integral?

Yes, most calculators have a built-in function for solving definite integrals. However, it is important to understand the concepts and techniques behind integration rather than solely relying on a calculator.

4. How do I check if my solution to a definite integral is correct?

You can check your solution by taking the derivative of the integrated function and evaluating it at the limits of integration. The result should match the original integrand.

5. Can definite integrals be used in real-world applications?

Yes, definite integrals have various applications in physics, engineering, and economics. They can be used to calculate areas, volumes, and even the work done by a force.

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