1. If x(t) is periodic with period 2.1 seconds and y(t) is periodic with period 2.4 seconds, is x(t)+y(t) periodic? Why or why not?
2. If x[n] is periodic with period 15 seconds and y[n] is periodic with period 10 seconds, is x[n]+y[n] periodic? What is the period?
3. If x(t) is periodic with period 2 seconds and y(t) is periodic with period 4 seconds, is x(t)+y(t) periodic? Why or why not?