If you want to write mathematical formulas in your LibreOffice document using LaTeX syntax, the TexMaths extension by Roland Baudin is what you are looking for. Installing it is pretty simple, just download the .otx file and you are done.
In order to work correctly, though, it requires that you have one of dvipng or dvisvgm installed. The former usually comes with your LaTeX installation and it is enough if you don't want support for vector graphics. I do like the svg format more though, which I think renders much more nicely in your documents, especially in presentation where you might want to use larger fonts.
dvisvgm is available on sourceforge and installing it from the source code is pretty straightforward. Here I will explain how to perform a system-wide install in Ubuntu 12.04. Read the INSTALL file that comes with the code if you have other needs.
First of all you need to download the package and extract it to a folder of your choice. Next open a terminal and cd to the folder where you have extracted the source code. Here issue the command