Question

If you have more numbers in your range then domain is it still a function?

Answer 1

yes it is .but no extra numbers in domain which are unmapped is possible.

Answer 2

ok thank you.. then I don't understand why this isn't a function: Explain why there does not exist a function whose domain is {-1, 0, 3} and whose range is {3, 4, 7, 9}.

Answer 3

If the range is bigger than the domain it is NOT a function. That means that one of your x values had to have mapped to MORE than one y value. That is the definition of a function.
For example:
x=y^2 For y=2 and -2 you get x=4. NOT a function.