Answer
a) $ f(9) = -7$
b) Domain: All real numbers
Range : $\{ -7\}$
Work Step by Step
Given \begin{equation}
f(x)=-7.
\end{equation} A) The function $f(x)$, has a constant value equal to $-7$ for any value of $x$. Hence $$ f(9) = -7.$$ B) Domain: All real numbers.
Range : $\{ -7\}$
