Question

How do you find [f • g](x) and [g • f](x) if `F(x) = x^2 + 2x` and `G(x) = x-9`?

Answer 1

`(f•g)(x)=x^2-16x+63`
`(g•f)(x)=x^2+2x-9`

Explanation:

`(f•g)(x)=f(g(x))=f(x-9)=(x-9)^2+2(x-9)`
`(f•g)(x)=x^2-18x+81+2x-18=x^2-16x+63`

`(g•f)(x)=g(f(x))=g(x^2+2x)=x^2+2x-9`