You define the range and domain as part of making the graph. For example:
In A1 thru A5 enter 1 thru 5
in B1 enter =SQRT(A1*A1-1) and copy down thru B5
You should see:
1 0
2 1.732050808
3 2.828427125
4 3.872983346
5 4.898979486
and then plot the graph. You have defined the range and domain.