is the new thing and again 
. Hey there this is \sqrt{\alpha} in an inline paragraph, which is great, even better than \infty
\begin{cases} \dfrac{1}{x}+\dfrac{1}{y} =\dfrac{1}{20} \\
x+2y=3
\end{cases}Ecuación con paréntesis
\big(x-2\big)\big(x^2-36\big)\big(x^2+5x\big)=0
Y ahora un límite con 
:
\lim_{x\to \infty} \frac{1} {x}\cdot \sqrt{x^2+3x}
\overset{IND\atop \big(0 \cdot \infty\big)} {\underset{\big\uparrow \atop Convertir:\frac{\infty}{\infty}}{=}}
\lim_{x\to \infty} \frac{\sqrt{x^2+3x}}{x}
\overset{IND\atop \big(\frac{\infty}{\infty}\big)}{\underset{\big\uparrow \atop Regla\, II}{=}}
\lim_{x\to \infty} \frac{\sqrt{x^2}}{x}=1
