For the Given Functions F and G, Find the Requested $\begin{array} { l } f ( x ) = x + 6 ; g ( x ) = 3 x ^ { 2 } \\ { Find } f + g\end{array}$

Multiple Choice

For the given functions f and g, find the requested function and state its domain.
- $\begin{array} { l } f ( x ) = x + 6 ; g ( x ) = 3 x ^ { 2 } \\ { Find } f + g\end{array}$

A) $( f + g ) ( x ) = - 3 x ^ { 2 } + x + 6$ ; all real numbers
B) $( f + g ) ( x ) = 3 x ^ { 2 } - x - 6 ;$ all real numbers
C) $( f + g ) ( x ) = 3 x ^ { 2 } + x + 6 ; \{ x \mid x \neq - 6 \}$
D) $( f + g ) ( x ) = 3 x ^ { 2 } + x + 6$ ; all real numbers