unreal ingot
The english word "evaluate" has different meanings. I think you are looking for an appropriate translation in the meaning of "to determine, to calculate, to find" as you already stated in your answer, "bewerten/evaluieren" wouldn't work here. You should rather use sth. like "bestimmen/ermitteln" (to determine), "berechnen (to calculate)" or "finden" (to find), e.g. "Bestimmen Sie die Ableitung (der Funktion ...)"
And regarding you last question, yeah, you could phrase your sentences like that. You could also say sth. like "Verwenden Sie die Formel <formula>, um [...]" in the meaning of "Use the formula <formula> to [...]"
blazing path