The parent function of the functions of the form f(x)=√x−a+b is f(x)=√x . Note that the domain of f(x)=√x is x≥0 and the range is y≥0 . The graph of f(x)=√x−a+b can be obtained by translating the graph of f(x)=√x to a units to the right and then b units up.
