Several factors can be responsible, including: 1  Heredity: If your dad had oily hair, chances are you will, too. 2  Hormonal fluctuations: In adult women, it may come with the menstrual cycle or using birth control pills. 3  Bulking up: Excessive oil is a side effect of using androgenic hormones to increase body mass.
At first glance, a function looks just like a relation. 1  It's a set of ordered pairs such as { (0,1) , (5, 22), (11,9) }. 2  Like a relation, a function has a domain and range made up of the x and y values of ordered pairs.
In modern mathematics, a function is defined by its set of inputs, called the domain; a set containing the set of outputs, and possibly additional elements, as members, called its codomain; and the set of all input-output pairs, called its graph.or example, we could define a function using the rule f (x) = x 2 by saying that the domain and codomain are the real numbers, and that the graph consists of all pairs of real numbers (x, x 2). The image of this function is the set of non-negative real numbers.