en.wikipedia.org/wiki/Proof_that_e_is_irrational Proof that e is irrational The number e was introduced by Jacob Bernoulli in 1683. More than half a century later, Euler, who had been a student of Jacob's younger brother Johann, proved that e is irrational; that is, that it cannot be expressed as the quotient of two integers. Euler's proof Euler wrote the first proof of the fact that e is irrational in 1737 (but the text was only published seven years later).[1][2][3] He computed the representation of e as a simple continued fraction, which is e=[2;1,2,1,1,4,1,1,6,1,1,8,1,1,・・・ ,2n,1,1,・・・ ]. Since this continued fraction is infinite and every rational number has a terminating continued fraction, e is irrational. A short proof of the previous equality is known.[4][5] Since the simple continued fraction of e is not periodic, this also proves that e is not a root of a quadratic polynomial with rational coefficients; in particular, e2 is irrational.
