Unless otherwise stated, the domain of any polynomial is always .

It always helps to sketch the graph to start with.

So the domain of is .

It's range is also .

To find the inverse, your x and y (or in this case, f) values swap, and so do the domain and range.

Since the domain and range of were both , so are the domain and range of .

Now we just find what the inverse function is.

.

Now graph this function.