f(x)=1/(x-1) calculez f'(x) et f(x). calculez f(x). (20 fois)

f'(x) = -1/(x-1)² = -(x-1)^-2
f''(x) = 2(x-1)^-3
f'''(x) = -2.3(x-1)^-4
f""(x) = 2.3.4(x-1)^-5
tu continues ainsi jusque 20 tu as vu le système
f20 (x) = 20!(x-1)^-21