# Doubt about the Fourier transform of one formula.

well, the formula is as follow:

but i am pretty sure that this answer - zero is not correct, so could anyone help me out of this problem?

• $F[\dot{x}(t)] = j \omega X(\omega)$ so $F[\dot{x}(t)^2] = (j \omega X(\omega)) \ast (j \omega X(\omega))$ – reuns Apr 10 '17 at 8:36
• your answer is correct, and i can totally understand that, but i want to know the exact result of F[g(t)]. can you help me with that? – amos Apr 10 '17 at 10:43
• Can you use what I wrote for obtaining the correct formula for $F[g(t)]$ ? – reuns Apr 10 '17 at 11:37
• does that matter? but i still cannot find my mistake. – amos Apr 10 '17 at 13:58
• i am sorry if that makes it not readable since i don't know about how to edit formula on the website, so i just upload the pictures. – amos Apr 10 '17 at 14:01

$F[x(t)\ddot x(t)]=-\omega^2X(\omega)*X(\omega)$
$F[\dot x(t)^2]=j\omega X(\omega)*j\omega X(\omega)\neq-\omega^2X(\omega)*X(\omega)$
• $\ne -\omega^2 X(\omega) \ast X(\omega)$ – reuns Apr 12 '17 at 1:30