Question

How do you find `[fog](x)` and `[gof](x)` given `f(x)=x-4` and `g(x)=3x^2`?

Answer 1

The answers are
`[fog] (x) =3x^2-4`
`[gof] (x)=3(x-4)^2`

Explanation:

This is a composition of functions

`f(x)=x-4`

`g(x)=3x^2`

`[fog] (x) =f(g(x))=f(3x^2)=3x^2-4`

`[gof] (x)=g(f(x))=g(x-4)=3(x-4)^2`