Question

If f(x)=-x+8 and g(x)= x^4 what is (g°f)(2)?

Answer 1

Notice, is really the same.  All we do is, "insert one function into the other".

so, a way to do it is, get the value of the first one, then insert that output into the second.

$\bf \begin{cases} f(x)=-x+8\\ g(x)=x^4\\ (g\circ f)(x)=g(~~f(x)~~) \end{cases} \\\\\\ (g\circ f)(2)=g(~~f(2)~~) \\\\\\ f(2)=-(2)+8\implies \boxed{f(2)=6} \\\\\\ g(~~f(2)~~)\implies g\left(~~\boxed{6}~~ \right)\implies g(6)=(6)^4\implies g(6)=1296$