Question

Let ​f(x)=x^2−12 and ​g(x)=13−x.
Perform the composition or operation indicated. ​(fg)(4​)

Answer 1

69

Explanation:

Rule:

`(fg)(x) = f(g(x))`

So,

`(fg)(4) = f(g(4))`

First solve g(4).

`g(4) = 13 - 4`

`g(4) = 9`

Plug g(4) into f(x).

`f(g(4)) = (g(4))^2-12`

`f(g(4)) = (9)^2-12`

`f(g(4)) = 81-12`

`f(g(4)) = 69`