Hello!
The answer is: The third option, 0.
Why?
We are asked to find (f-g) evaluated in 144, so the definition states that:
[tex](f-g)(x)=f(x)-g(x)[/tex]
So,
[tex]f(x)-g(x)=\sqrt{x} +12-2\sqrt{x}=-\sqrt{x} +12[/tex]
We must remember that evaluating a function means replacing the variable with the given value, for this case it's 144.
Then, evaluating:
[tex](f-g)(144)=-\sqrt{144}+12=-12+12=0[/tex]
Hence, if:
[tex](f-g)(144)=0[/tex]
The correct option is the third option, 0.
Have a nice day!
