How can the method of residues be used to solve integrals?

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SUMMARY

The integral of 1/(x^4+x^2+1) from 0 to infinity equals (π√3)/6, as demonstrated using the method of residues. The solution involved identifying the poles of the quartic equation x^4+x^2+1=0, which were found by substituting y=x^2 and applying the quadratic formula. The residues at the relevant poles were evaluated, and due to the even nature of the function, the result was halved to obtain the desired integral from 0 to infinity.

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[SOLVED] Integral using residues

Homework Statement


Show integral of 1/(x^4+x^2+1) from 0 to infinity equals (pi*sqrt(3))/6 using method of residues



Homework Equations





The Attempt at a Solution


Tried to solve x^4+x^2+1=0. Don't get very useful numbers for poles.
 
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Well what do you know about the method of residues? You've not really shown any work now, have you?
 
don't worry i worked it out. I didn't solve the quartic properly to get the poles before. I got my 4 poles two of which I am parts are more than 0. I evaluated the residues at those two poles and got the value. Since it's even I can divide that number by two to get the integral from 0 to inf rather than -inf to inf. I didn't notice there was a much easier way to solve that quartic by letting y=x^2 and then using quadratic formula to find y then x would be just the sqrt of y.
 
Well done!
 

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