Fuente TeX:

\displaystyle\lim_{x\to 0}\frac{f(x)}{x^3}=\lim_{x\to 0}\frac{T_{3,n,0}(x)+r_{3}(x)}{x^3}=\lim_{x\to 0}\frac{T_{3,n,0}(x)}{x^3}+\frac{r_{3}(x)}{x^3}=\lim_{x\to 0}\frac{T_{3,n,0}(x)}{x^3}