let f (x) =x (is under square root_)
g(x)=2x-1
h(x)=x^2

question is
(h.g.f) (9)

Is that what you mean:



Evaluate h(g(f(9)))

What you do is start with the inner-most function and evaluate it, then substitute its value into the next higher-level function, and so on. So here, you have:

Step 1:
Step 2:
Step 3:

I'm sure you can take it from here.