Respuesta :

hello : 
f(x) = 9x-6
g(x) =√(x-4)
(f0g)(x) = f(g(x)) exist if  g(x) exist  and    f(g(x)) exist.
g(1) no exist because :  √(1-4) =√(-3) ... no real
conclusion : 1 is not in the domain of : f0g