In my book and in other places, they give this rule to obtain the domain for
a compound function: "the domain of (f o g) (x) is the set of all real
numbers x such that g(x) is in the domain of f (x)."
Then, if f(x)=x^(1/4)
and
g(x)=x^2
f(g(x)) = (x^2)^(1/4)
f(g(x)) = x^(1/2)
And applying...