This integral taught me Feynman's technique

This is an integral from the 2005 Putnam exam. It's the first integral I had ever solved using Feynman's trick of differentiating under the integral sign and I think it's one of the best examples on how to apply the technique. My complex analysis lectures: https://youtube.com/playlist?list=PLVkOfIPb514EP3CjWQQ-JmKpIiNoEUS0k&si=rdmwOkQ6Vxg64yrE If you like the videos and would like to support the channel: https://www.patreon.com/Maths505 You can follow me on Instagram for write ups that come in handy for my videos and DM me in case you need math help: https://instagram.com/maths.505?igshid=MzRlODBiNWFlZA== My LinkedIn: https://www.linkedin.com/in/kamaal-mirza-86b380252 Advanced MathWear: https://my-store-ef6c0f.creator-spring.com/