Question 1
I chose the signal $ x[n]=e^{j\pi n} \, $ which Jeff Kubascik posted on his HW1.
Recall that this signal is periodic if $ T = {\omega_0\over2\pi}\, $ is rational.
Say I choose the sampling period $ T_s=.1\, $
The output will be:
But if I choose the sampling period to be $ T_s=.7\, $