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Bepaalde lijnintegraal die de wortel van $\pi$ als uitkomst geeft

$
\int\limits_{ - \infty }^\infty {e^{ - x^2 } dx}
$

Dupon Erwin
6-2-2017

Antwoord

Once when lecturing in class, Lord Kelvin used the word mathematician and then interrupting himself asked his class: ‘Do you know what a mathematician is?’

Stepping to his blackboard he wrote upon it:
$$
\int_{-\infty}^\infty e^{-x^2}\mathrm{d}x=\sqrt\pi
$$
Then putting his finger on what he had written, he turned to his class and said, ‘a mathematician is one to whom that is as obvious as that twice two makes four is to you. Liouville was a mathematician.’ Then he resumed his lecture.

Zie Evaluating an integral [http://pages.pacificcoast.net/~cazelais/260/lord-kelvin.pdf]

kphart
6-2-2017