(ln(1+x))^2-X^2/(1+x)

(ln(1+x))^2-X^2/(1+x)

t=x+1
f(t)=(lnt)^2-(t-1)^2/t=(lnt)^2-(t-2+1/t)
면 f'(t)=2(lnt)/t-1+1/t^2=1/t*[2lnt-t+1/t]
g(t)=2lnt-t+1/t
g'(t)=2/t-1-1/t^2=-(1/t-1)^2