Question

How do you determine `f(g(x))` if `ƒ(x)=x(x + 1)` and `g(x)=x^2−1`?

Answer 1

As you can have, for example, `f(3)` where, in your function, you set `x=3` you can do the same here; the only difference is that you do not have a number but na entire function `g(x)=x^2-1` to substitute.
You get:

`f(g(x))=f(x^2-1)=(x^2-1)[(x^2-1)+1]=`

`=(x^2-1)x^2=x^4-x^2`