I finally learned how. It's a little simple; first the domain will usually always be All real #'s. Range is determined by the vertical shift of the functions(last part of the function) y=(3^x)-6 so y>-6
1) your domain is all reals, and the Range is all positive real numbers. The graph shifted down 6 units.
2)here your domain and range will be all reals. The graph is a line with negative slope and y intercept at (0,2)