Công thức nào sau đây là chính xác:

$\text{I}\text{F}\text{T}\left[\text{X}\left(\text{e}{}^{\text{j}\omega }\right)\right]=\frac{1}{2j\pi }{{\displaystyle \int }}^{\omega }\mathrm{Unsupported\; }X\left(e{}^{j\omega }\right)\cdot e{}^{j\omega s}d\omega$

$\text{I}\text{F}\text{T}\left[\text{X}\left(\text{e}{}^{\text{j}\omega }\right)\right]=\frac{1}{2j\pi }{{\displaystyle \int }}^{\pi }\mathrm{Unsupported\; }X\left(e{}^{j\omega }\right)\cdot e{}^{j\omega s}d\omega$

$\text{I}\text{F}\text{T}\left[\text{X}\left(\text{e}{}^{\text{j}\omega }\right)\right]=\frac{1}{2\pi }{{\displaystyle \int }}^{\pi }\mathrm{Unsupported\; }X\left(e{}^{j\omega }\right)\cdot e{}^{j\omega t}d\omega$

$\text{I}\text{F}\text{T}\left[X\left(\text{e}{}^{\text{j}\omega }\right)\right]=\frac{1}{2\pi }{{\displaystyle \int }}^{\omega }\mathrm{Unsupported\; }X\left(e{}^{j\omega }\right)\cdot e{}^{-j\omega s}d\omega$