A friend of mine was the TA for a graduate level Math course for Physicists. And an exercise in that course was to solve integrals using Contour Integration. Just for fun, I decided to mess with him by trying to solve all the contour integral problems in the prescribed textbook for the course [Arfken and Weber’s ‘Mathematical methods for Physicists,7th edition” exercise (11.8)] using anything BUT contour integration.
You can solve a lot of them them exclusively by using Feynman’s trick. ( If you would like to know about what the trick is – here is an introductory post) The following are my solutions:
Arfken-11.8.6 & 7 – not applicable
Arfken-11.8.21 & Arfken-11.8.23* (Hint: Use 11.8.3)
*I forgot how to solve these 4 problems without using Contour Integration. But I will update them when I remember how to do them. If you would like, you can take these to be challenge problems and if you solve them before I do send an email to 153armstrong(at)gmail.com and I will link the solution to your page. Cheers!