Let x(t) denote a periodic signal with time period T with exponential Fourier series coefficients ak. The Fourier series coefficient (bk) of the composite signal y(t) = x (3 - t) can be given by
1
\({e^{ - jk\frac{{3\pi }}{T}}}{a_{ - k}}\)
2
\({e^{ - jk\frac{{2\pi }}{T}}}{a_{ - k}}\)
3
\({e^{ - jk\frac{{6\pi }}{T}}}{a_{ - k}}\)
4
\({e^{jk\frac{{6\pi }}{T}}}{a_k}\)