The general expression for an exponential function is the following:
where b represents the base of the function.
In this case, notice that the graph of the function passes through the points (0,1) and (1,1/3), then, with these points we can find the values of a and b:
therefore, we have that:
the initial value is a = 1
the base is b = 1/3
the domain of the function is all real numbers.