Bonsoir
A) f(x) = -1/2x +3 f ' (x) = -1/2 f ' (0) = -1/2
B) f(x) = 2x²-4x f ' (x) = 4x - 4 f ' (1) = 0
C) f(x) = 2x-1/x f' (x) = 2+1/x² f ' (-1) = 1
D) f(x) = 5/x f ' (x) = -5/x² f ' (2) = -5/4
E) f(x) = -3/x + 2 f' (x) = 3/x² f ' ( 3) = 1/3
F) f(x) = x^3-3x+1 f ' (x) = 3x² -3 f ' (1) = 0