y=ln[(1-x)/(1+x)]
y' = [(1+x)/(1-x)] .[-(1+x)- (1-x)/(1+x)^2]
=-2/[(1+x)(1-x)]
= -[ 1/(1+x) +1/(1-x) ]
y'' =-[-1/(1+x)^2 + 1/(1-x)^2 ]
y^(n)x = -(n-1)!.[ (-1)^(n-1) /(1+x)^n + 1/(1-x)^n]
求y=ln[(1-x)/(1+x)]的高阶导数y(n) 急,
y=ln[(1-x)/(1+x)]
y' = [(1+x)/(1-x)] .[-(1+x)- (1-x)/(1+x)^2]
=-2/[(1+x)(1-x)]
= -[ 1/(1+x) +1/(1-x) ]
y'' =-[-1/(1+x)^2 + 1/(1-x)^2 ]
y^(n)x = -(n-1)!.[ (-1)^(n-1) /(1+x)^n + 1/(1-x)^n]