lim(1/ln(1+x)-1/x)
=lim[x-ln(1+x)]/xln(1+x)
=lim[1-1/(1-x)]/[ln(1+x)+x/(1+x)]
=limx/[x+(1+x)ln(1+x)]
=lim1/[ln(1+x)+1+1]=1/2