What is the value of ∫−∞∞12πe−x2/2dx\int_{-\infty}^{\infty} \frac{1}{\sqrt{2\pi}} e^{-x^2/2} dx∫−∞∞2π1e−x2/2dx?
000
111
π\piπ
2π\sqrt{2\pi}2π