Hello,

The function is an even function ie

--------->

Now, let's integrate.

At first sight, you have to use the integration by parts, this must be almost a reflex when you see an exponential. The exponential will very often take the place of the v' function in :

So you must make appear the derivate of , 2x, so as to be able to integrate :

the integrate of will simply be

------ integration by parts ------

the derivate of is

(the two limits tend to 0)

In the same way, make appear the derivate of so as to integrate once again by parts.

And there, i can't help anymore because of the last integral : i don't remember how to do