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...Differentiating under the integral sign keith conrad i had learned to do integrals by various methods shown in a book that my high school physics teacher mr bader given me showed how dierentiate parameters it s certain operation turns out not taught very much universities they don t emphasize but caught on use method and used one damn tool again guys at mit or princeton trouble doing come along try dierentiating often worked so got great reputation for only because box of tools was dierent from everybody else tried all their before giving problem richard feynman introduction themethodofdierentiationundertheintegralsign dueoriginally leibniz concerns r tx depending parameter such as x e dx here is extra since variable integration general we might write an z bf where f function two variables like example let then anti derivative with respect this answer which makes sense integrand depends integrate over are left something rbf can ask about its assuming nicely behaved rule called dierenti...