the function is even when

Question

a. all of the option mentioned b. f(x) = - f(x) for all x c. f (x) = f(-x) for all x d. f(x) = f(x) for all x

Answer 1

An even function is symmetrical about the vertical axis (which acts like a mirror), so f(x)=f(-x) (answer c). An example of an even function is f(x)=x².