Answer
$f(g(x)) = 5-x$
Since the function $f(g(x))$ is a polynomial function, its $Domain$ is $all$ $Real$ $numbers$
Work Step by Step
$$f(x) = x^2 +4$$ $$g(x) = \sqrt{1-x}$$
$f(g(x)) = (\sqrt{1-x})^2 +4$
$f(g(x)) = (1-x) +4$
$f(g(x)) = 5-x$
Since the function $f(g(x))$ is a polynomial function, its $Domain$ is $all$ $Real$ $numbers$
