Binary operation that associates every ordered pair (

*f*,*g*) of functions, defined on a set*E*to a set*F*, with a new function written as*f*•*g*and called the product of these functions.To obtain the value of the product of two functions

*f*and*g*with a variable*x*, the images*f*(*x*) and*g*(*x*) are multiplied: (*f*•*g*)(*x*) =*f(*x*) ×*g*(*x*).*