Question: How to enter the general case f(x) ?

Given a function like f(x)=2*x

I can enter this in Flow 2022 like this ...  f := x -> 2*x;

1 - But how to enter the general case f(x) where the function is not defined beyond just f(x)?

2 - And ultimately how to enter the below?

In either case ...

Since f(x) is the general case and not defined as in my intial example above ...
I can't figure out how to enter this into Flow 2022

Thanks for any help.

System: Windows 10 Pro 64-bit

Maple Flow 2022

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