Answer:
f'(x) doesn't exist at x=2 in (0,4)
g'(x) exist over (0,4). 
Step-by-step explanation:
We are given a graph and need to find the point derivative does not exist.
Black: Graph of f(x)
Blue: Graph of g(x)
In interval (0,4)
f(x) is graph of absolute function. At x=2, f(x) has vertex or corner.
As we know function is not differential at corner.
Hence, f'(x) doesn't exist at x=2 in (0,4)
g(x) is graph of straight line. Derivative of straight line is constant. g(x) is differential over (0,4)
Hence, g'(x) exist over (0,4). 