Question Number 30542 by abdo imad last updated on 23/Feb/18
$${prove}\:{that}\:\:\int_{\mathrm{0}} ^{{x}} \:\:{e}^{−{u}^{\mathrm{2}} } {du}=\:{x}\:\int_{\mathrm{0}} ^{\frac{\pi}{\mathrm{4}}} \:\:\frac{{e}^{−{x}^{\mathrm{2}} {tan}^{\mathrm{2}} {t}} }{{cos}^{\mathrm{2}} {t}}{dt}\:\:. \\ $$$$ \\ $$