The DOMAIN is the set of all possible numbers that you can put in for the independent variable and get an answer. If you had g(x) = 1/x, you could NOT put in 0 for x and get an answer because 1/0 is undefined. So the domain is all numbers but 0.
The RANGE is the set of numbers you will get for the dependent variable. If you had g(x) = 1/x, you could NOT get 0 for g(x), no matter what you put in for x. So the range is all numbers but 0.
the domain and the range equal all possible numbers. Or all real numbers