Then you can figure out which is the independent variable and which is the dependent variable: (Independent variable) causes a change in (Dependent Variable) and it isn't possible that (Dependent Variable) could cause a change in (Independent Variable). For example: (Time Spent Studying) causes a change in (Test Score) and it isn't possible that (Test Score) could cause a change in (Time Spent Studying).
Domain and Range. When we look at a function like f(x) = x + 2, we can easily say where the function f(x), in this case, the value along the y-axis, is at any point we choose along the x-axis. We know that at x = 3.4, f(x) = 5.4. The values of x that the function will output a value for is called the domain of f. In the case of f(x) = x + 2, the domain is the entire x-axis, or, formally speaking, all real numbers. The values which f(x) takes on is called the range of f.
Once the domain has been defined, then the values of y that correspond to the values of x are called the range. Thus if 5 is a value in the domain of y = 2x + 3, then 13 (2Â· 5 + 3) is the corresponding value in the range. By the value of the function we mean the value of y. And so when x = 5, then we say that the value of the function y = 2x + 3, is 13. The range is composed of the values of the function.