Answer:
none of the above
Step-by-step explanation:
This question wants you to see that the radical can be simplified because it is ...
[tex]f(x)=\sqrt{(x+6)^2}[/tex]
The answer choices show you are expected to simplify this to ...
... f(x) = x +6
Then
... f(x)·g(x) = (x+6)(x³ -12) = x⁴ +6x³ -12x -72 . . . . . matches choice C
_____
However,
... f(x) = |x+6| . . . . . . . √(x^2) = |x|, the positive root regardless of sign of x
so the product f(x)·g(x) only matches selection C for x≥ -6. It matches the opposite of selection C for x ≤ -6.
The attached graph shows this. It graphs f(x), g(x), f(x)·g(x) (as a purple curve), and selection C (as orange dots).
