1. The problem statement, all variables and given/known data We are given a table where showing the points x and y and values of a function f(x,y). The function itself is not given. I have to find the partial derivatives f'x, f'y, f''xx, f''yy and f''xy around the point (2,3). 2. Relevant equations I have to use the definition : f'x(2,3) = lim (h-->0) [f(2+h,3) - f(2,3)] / h 3. The attempt at a solution Ok. So I easily found f'x and f'y. (h is found by looking at the xs and ys, h for f'x = -1 and 2 for f'y). My problem is finding the f''. My teacher is the kind that shows one definition and gives one example. I don't know how to find the f''s. If someone could just point the way, I'd be grateful. Thanks!