Lema
[tex3]\hspace{70pt}\lim_{x \to \infty}\,\, \left(1 \,+\,\frac{k}{x}\right)^x\,=\,e^k\cdot [/tex3]
[tex3]\hspace{70pt}\lim_{x \to \infty}\,\, x^2\,\cdot\, \ell n\,\left(\frac{x^2 \,+\,4}{x^2\, +\,1}\right)\,=\,\lim_{x \to \infty}\,\, \ell n\,\left(\frac{x^2 \,+\,4}{x^2\, +\,1}\right)^{x^2}[/tex3]...