Hey,

How would you solve the following integral:

$\displaystyle

\int_{-\infty}^{\infty} e^{-x^2/2}dx

$

I've been trying to use a substitution, but I kind of forgot how to do it exactly. I've tried both polar and cylindrical coordinates, but I can't crunch it to the right answer. Any help? Sorry its been a while since I've done this type of integral.