Functional Equations: A functional equation is an equation, which relates the values assumed by a function at two or more points, which are themselves related in a particular manner. For example, we define an odd function by the relation f(-x)=-f(x) for all x. This definition can be paraphrased to say that it is a function f(x), which satisfies the functional relation f(x)+f(y)=0, whenever x+y=0. Of course, this does not identify the function uniquely, sometimes with someadditional information, a function satisfying a given functional can be identified uniquely. Suppose a functional equation has a relation between f(x) and f((1)/(x)), then due to the reason that reciprocal of a reciprocal gives back the original number, we can substitute 1/x for x. This will result into another equation and solving these two, we can find (x) uniquely. Similarly, we can solve an equation, which contains f(x) and f(-x). Such equations are of repetitive nature. In the functional equation given in previous question, if a+b=0, then f(x) is equal to