when f(x)=x^2 and g(x)=x-3 what is f(g(x))and how do you do it?
g takes x to x-3. That is, start with x, then g(x) will be three less. 5 -> 2, 11-> 8, 1 -> -2. Right?
f squares x, so f(5)=25. Similarly, 3-> 9, 8 -> 64, and so on.
f(g(x)) just means "do g on x, then do f on the result". If you start with x=5, then g will bring that to 2, and doing f on 2 will bring that to 4.
So how do you combine them? Just write down g(x), and then do an f on it.