Find the Function $f \cdot g$ And Its Domain If $f ( x ) = \sqrt { x + 7 }$

Multiple Choice

Find the function $f \cdot g$ and its domain if $f ( x ) = \sqrt { x + 7 }$ and $g ( x ) = \sqrt { x - 7 }$ .

A)
$\sqrt { x ^ { 2 } - 49 }$
$D = [ 7 , \infty )$

B) $\sqrt { x ^ { 2 } - 49 }$
$$D = [ - 7 , \infty )$$

C)
$$\begin{array} { l } \sqrt { x ^ { 2 } + 49 } \\D = [ - 7 , \infty ) \end{array}$$
D) $\sqrt { x ^ { 2 } + 49 }$
$$D = [ 7 , \infty )$$