The only function which is both even and odd is the constant function which is identically zero (i.e., f(x) = 0 for all x). In general, the sum of an even and odd function is neither even nor odd; e.g. x + x2. The sum of two even functions is even, and any constant multiple of an even function is even.
previous (odd fn) link:
https://youtu.be/XJVdArdAqaI
