Question 2.7. Show that for all periodic physical signals that have finite power, the coefficients of the Fourier series expansion $ x_n $ tends to 0 as $ n \to \infty $
I have computed $ |x_n|^2 $ by multiplying $ x_n $ with $ x_n^*$. However, as per my calculations, $ |x_n|^2 = P_x $ i.e. power of $ x(t) $, which is a constant and independent of $n$. I know that this is fundamentally incorrect because $ |x_n| $ should vary with $n$. If anyone can guide me about where I went wrong that would be very helpful. Thanks and regards.
Please refer to the solution from the half of the first page.