Sketched line of a generator is represented by the function approximation
How do I calculate for which value of resistance R generators shows the biggest power?
I am guessing that those commas are there to represent decimals. So 0,2 is 0.2 right?
Still have to get used to seeing that, if that is what it really is.
Yes, for a function F(x) the critical points can be found by solving:
dF(x)/dx=0
What you should do then is ask if the units work out.
You want units of power.
Does Uo*I/U have units of power?
Each term of the right hand side needs to have units of power. Since you still can't be bothered to track your units, it is impossible to tell what the units are for most of the terms. But what about that first term, I ? Does it have units of power?
Always, always, ALWAYS track your units and check them. Otherwise you will blithely go chasing rabbits down holes when you could and should have known from the early on that your work was guaranteed to produce the wrong answer.