The Function is even, if for any two numbers, which are additive inverse, the values of a function are equal. f(-x) = f(x) The Function is even, because for additive inverse numbers (e.g. -3, 3) values are the same. Examples of even functions: y = |x|, y = x^2, y = cos x. The Function is odd, if for any two numbers, which are additive inverse, the values of a function are additive inverse too. f(-x) = -f(x) The Function is even, because for additive inverse number (e.g. -5, 5) the values are additive inverse too. Examples of odd functions: y = x^3, y = 1/x, y = sin x. The Function is neither even nor odd. That is in most cases.