You're welcome.
Do you know the definition of a vector space?
Maybe you're looking for something like : http://www.mathhelpforum.com/math-he...tor-space.html, http://www.mathhelpforum.com/math-he...ace-proof.html and http://www.mathhelpforum.com/math-he...bspaces-v.html.
Of course there are much more related threads if you start to search.