I'm having a bit of trouble with some basic gaussian integrals. I've not looked at this sort of stuff in ages.

The first example on the sheet I've been given (note, this sheet isn't homework or being marked/assessed, so I can ask for help!) is the following:

Wherexis anncomponent vector andAis a real symmetric matrix.

My first question is: if I take the vectors to have just one component, is the solution:

?

Also, how would you go about solving the original general case?