Math Markup Example

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$\mathrm{erfc}(x)=\frac{2}{\sqrt{\pi }}{\int }_x^{\mathrm{\infty }}{e}^{-t^2}dt=\frac{e^{-x^2}}{x\sqrt{\pi }}\sum _{n=0}^{\mathrm{\infty }}(-1{)}^n\frac{(2n)!}{n!(2x{)}^{2n}}$