Answer:
The third
Step-by-step explanation:
[tex](g\circ f)(x) = g\big(f(x)\big)[/tex]
so:
[tex]I.\quad (g\circ f)(a)=\sqrt{f(a)}=\sqrt{a^2-4}=\sqrt{(a+2)(a-2)}\\\\II.\quad (g\circ f)(a)=2f(a)-2=2(\frac12a-1)-2=a-2-2=a-4\\\\ \bold{III.\quad (g\circ f)(a)=\sqrt{f(a)-5}-2=\sqrt{5+a^2-5}-2=\sqrt{a^2}-2=|a|-2}\\\\ IV.\quad (g\circ f)(a)=4f(a)-5=4(3-3a)-5 = 12-12a-5=-12a+7[/tex]
