Answer:
If
, then
is even.
If
, then
is odd.
Explanation:
Summary of rules/ what we need:
implies
is even.
implies
is odd.
So in either case, we need to replace
with
.
Let's begin.
First Problem:

Replace
with
:

(We used
is odd; that is,
)


This implies
is an even function.
Second Problem:

Replace
with
:

(We used
is even; that is,
)


This implies
is an odd function.