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**NecroWinter** Theres two derivative formulas being discussed in class, and the one is pretty much completely dominant. That is f(x+h)+f(x)/h

the other is f(b) - f(a)/b-a

my book doesnt really talk much about the second formula, but in its solution manual, it uses it quite a lot without every explaining why thats the preferred choice. While attempting to use the first formula on some problems, I can see why it would be hard, but how does one know before hand which formula to use? Is there a rule of thumb?

thanks