Question

x^2/(1-x)的n阶导数

Answer 1

y = x^2 /(1-x) = (x^2 -1 + 1) /(1-x) = - (x+1) + 1/(1-x)
y ' = -1 + 1/(1-x)^2
y '' = 2!/ (1-x)^3
y 的n阶导数：n!* (1-x)^(-n-1)