Perform the Requested Operation on the Given Function $$f ( x ) = 4 \sqrt { x - 6 } , g ( x ) = 2 \sqrt { x - 6 }$$

Multiple Choice

Perform the requested operation on the given function.
- $$f ( x ) = 4 \sqrt { x - 6 } , g ( x ) = 2 \sqrt { x - 6 }$$
Find $( f + g ) ( x )$

A) $6 x + 6$
B) 6
C) $6 \sqrt { x - 6 }$
D) $6 \sqrt { 2 x - 12 }$