Brilliant answer to a difficult math problem

Last time when I was in school, calculus took the life out me. I see around me, I see everyone is completely comfortable with this weirdo branch of mathematics and in fact doing pretty well in the exam too. Unfortunately, I was the definite stigma among a bright Math oriented group of intelligent students, in fact, even until today I’m scared of this Math thing.
However, when I saw the following brilliant answer to such a difficult math problem, I immediately started to realize, I am not the lonely one in this lost world of Calculus.