Solution to Q1 of Week 13 Quiz Pool
Suppose $ X(w)\,\! $ is the DTFT of a discrete-time signal $ x[n]\,\! $.
What is the DTFT of the time-reversal $ x[-n] $?
$ \begin{align} & \sum_{n=-\inty}^{\infty} x[-n]e^{-jwn} \\ & \quad (\text{change of variable} \;\; m=-n) \\ = & \sum_{m=-\inty}^{\infty} x[m]e^{jwm} = X(-w) \\ \end{align} $
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