Expert: Ahmed Salami - 5/13/2010

Question
could you please let me know the trick to finding the answer to the formula,   [f(x-(delta)x)-f(x)divided by: (delta)x]?    (sorry i wasnt able to paste the formula directly, so it may be difficult to decifer. Thanks a lot!
                                Alan

Answer
Hi Alan,
If you mean to refer to [f(x + Δx) - f(x)]/Δx, then it is the expression whose limit, as Δx approaches zero, is the derivative (rate of change) of f(x) with respect to x.
It is written as;
f'(x) = lim(Δx→0) [f(x + Δx) - f(x)]/Δx

You can always get back to me as i wasnt sure exactly what you wanted.

Regards