Maxima and minima without calculus

Ivan Morton Niven was a Canadian-American mathematician, specializing in number theory and known for his work on Waring's problem. He worked for many years as a professor at the University of Oregon, and was president of the Mathematical Association of America. -- Wikipedia Image from Oberwolfach Photo Collection (Konrad Jacobs, Erlangen, Photo ID: 3069) Creative Commons License Attribution-Share Alike 2.0 Germany