For ϵ↓0, put L=log(1/ϵ). Taking a logarithm gives x2+logx=L, first implying x∼L. Substitution of x=L+d gives 2Ld+21logL at first correction order. Hence d=−(logL)/(4L); substituting back and using the derivative of x2+logx bounds the remaining root error by O((logL)2/L3/2).