Test

[math]\operatorname{erfc}(x) = \frac{2}{\sqrt{\pi}} \int_x^{\infty} e^{-t^2}\,dt = \frac{e^{-x^2}}{x\sqrt{\pi}}\sum_{n=0}^\infty (-1)^n \frac{(2n)!}{n!(2x)^{2n}}[/math]

<tex>

 \operatorname{erfc}(x) =
 \frac{2}{\sqrt{\pi}} \int_x^{\infty} e^{-t^2}\,dt =
 \frac{e^{-x^2}}{x\sqrt{\pi}}\sum_{n=0}^\infty (-1)^n \frac{(2n)!}{n!(2x)^{2n}}
</tex>

[math]x^2[/math]

<tex> x^2 </tex>