2
$\begingroup$

I want to show $\displaystyle \sum_{n=2}^{\infty}\frac{\cos nx}{\log n}$ is a Fourier series but i am stuck how to show the given series is a Fourier series. Can anybody help me?

  • 2
    @nbubis He wants to show there is actually some function with that Fourier series, not just that it is of the form that Fourier series are in. If you replaced $\cos nx$ with $\sin nx$ the theorem I linked to shows there is no function with that Fourier series.2012-04-21

0 Answers 0