We have the function;
[tex]f(x)=-2x+8[/tex]and
[tex]g(x)=\sqrt[]{x+9}[/tex]Let's obtain f(g(x) before we make conclusions on the statements.
[tex]f^og=-2(\sqrt[]{x+9})+8[/tex]The domain of f(g(x) starts from x= - 9, this is where the function starts on the real line.
But - 6 < -9 , and thus,
The answer is - 6 is in the domain of the function.