function In algebra, y is a function of x can be written as y = f(x). In the case of y = 2x + 1, the specific rule for mapping x into y is "double x and then add 1 to obtain y value." Some of the specific mappings are listed below:     x         y         :         :         -2.0         -3.0         -1.0         -1.0         0.0         1.0         1.0         3.0         2.0         5.0