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CalculusMediumNon-Elementary Integration

Non-Elementary Integration · Medium problem

The error function erf⁡(x)=2π∫0xe−t2 dt\operatorname{erf}(x)=\dfrac{2}{\sqrt\pi}\displaystyle\int_0^{x}e^{-t^2}\,dt has no elementary formula, and erf⁡(x)→1\operatorname{erf}(x)\to1 as x→∞x\to\infty. Use integration by parts to evaluate ∫0∞(1−erf⁡(x)) dx\displaystyle\int_0^{\infty}\bigl(1-\operatorname{erf}(x)\bigr)\,dx.