Problem #1
CT equation that is periodic:
$ y[n] = sawtooth[n] $
N is an integer for the DT equations.
DT equation that is non-periodic:
$ y[n] = sawtooth[100N] $
DT equation that is periodic:
$ y[n] = sawtooth[\frac{\pi}{2}N] $
Problem #2
$ y[n] = e^{n-kN} * sin[n-kN] $ is the non-periodic equation.
To make it periodic:
$ \sum_{k=0}^{\infty} e^{n-kN} * sin[n-kN] $
