Let f (x) be differentiable at x = A and lim [f (a + 5H)] - f (a-5h)] / 2H = 1, then f '(a)=

Let f (x) be differentiable at x = A and lim [f (a + 5H)] - f (a-5h)] / 2H = 1, then f '(a)=

The limit formula can be reduced to 5 / 2 (f '(a) + F' (a)) = 1, that is, 5F '(a) = 1, f' (a) = 1 / 5;