Functions

 

Functions (Explicit functions)

The variable y is said to be a function of x (an explicit function), if to every value of x within a certain set of values there is one and only one corresponding value of y. We write, y=f(x). Here, f is the name of the function.

 

Independent and dependent variables

The variable in a function on which the value of the other variable depends. If y=f(x), x is the independent variable and y is the dependent one.

 

The domain of a function

The set of values the independent variable takes in a function.

 

The range of a function

The set of all values the dependent variable may take corresponding to all values of the independent variable.

Implicit functions

If a function is written in the form f(x,y)=0 and cannot be solved for one variable in terms of another, we say that it is an implicit function in x and y. Here, if one of the two variables takes a value, there may be more than one corresponding values for the other variable. An example is: