we have

we know that
The graphs of inverse functions are a reflection over the line y = x. If you can see from the graphs that one is a reflection of the other over the line y = x, then that proves they are inverse functions
using a graph tool
see the attached figure------> you can see from the graph that one is a reflection of the other over the line y = x
therefore
the functions f(x) and g(x) are inverse functions
the answer is
Part a) see the attached figure
Part b) see the explanation above