We have the function;

and
![g(x)=\sqrt[]{x+9}](https://img.qammunity.org/2023/formulas/mathematics/college/vwg4kps9vx6xhx85zcxyphl1rzo9q586wu.png)
Let's obtain f(g(x) before we make conclusions on the statements.
![f^og=-2(\sqrt[]{x+9})+8](https://img.qammunity.org/2023/formulas/mathematics/college/xwjq9qpbqkmvciuuqzy7ore7whq3v688go.png)
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.