POlynomials (or Taylor series ) of the form(adsbygoogle = window.adsbygoogle || []).push({});

[tex] P(x)= \sum_{n}a_{2n}X^{2n} [/tex] with [tex] a_{2n}\ge 0 [/tex] strictly

have ALWAYS pure imaginary roots ??

it happens with [tex] sinh(x)/x [/tex] [tex] cos(x) [/tex] could someone provide a counterexample ? is there an hypothesis with this name ??

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# A question about zeros of polynomials

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