The domain of a function is the set of possible input values, the domain of a graph consists of all the input values shown on the x-axis.
The range is the set of possible output values, shown in the y-axis.
Then, for the given graph:
Domain: All real numers (a exponential function as the given can have values of x of all real numbers)
Range: THe range in the graph is the values in the y-axis, all y greather than 3.