How can I determine whether this is periodic or not.

1.

I can't find way to do of this due to summation.

2.

y1(t)=x(2t) and y2(t)=x(t/2)

I need to determine whether followings are true and find the fundamental period.

<1> if x(t) is periodic, then y1(t) is periodic.

<2> if y1(t) is periodic, then x(t) is periodic.

Could anybody help me plz?