Even functions

An even function f(x) for all values of x and –x holds

Options:

a) f(x) = f(-x)
b) f(x) = -f(x)
c) f(x) = f(x)f(-x)
c) none of the above

Correct Answer: a) f(x) = f(-x)

Explanation:

If f(x) is a real-valued function of a real variable then f is even if the following equation holds for all the values of x and –x.
f(x) = f(-x)
Or
f(x) - f(-x)= 0