What is the value of the integral ∫−∞∞12πe−x2/2dx\int_{-\infty}^{\infty} \frac{1}{\sqrt{2\pi}} e^{-x^2/2} dx∫−∞∞2π1e−x2/2dx?
111
2π\sqrt{2\pi}2π
000
1/2π1/\sqrt{2\pi}1/2π