The differential. Approximation
Until now we have been dealing with functions whose domain is a set of real numbers ( I,e, a set R1) and whose range is also a set of real numbers (a set in R1). Symbolically, if D is the set of numbers comprising the domain of a function f and S is the set of numbers comprising the range, we may write f:D-S. in the case of functions given by formulas, we write f(x ) = x2 -2x + 7 or f:x- x2-2x+7 to indicate the particular function.