As you may know, LyX is an open-source and multi-platform WYSIWYM/WYSIWYG document processor, using TeX / LaTeX behind some graphical user interface. It is ideal for writting academic articles, theses or books and has support for mathematical formulas.
The latest version available is LyX 2.1.4, which has been recently released, but unfortunately, the changelog is not yet available.
Up to date Lyx packages are available via some third party PPA, so installing the software on Ubuntu and derivative systems is easy. Just add the PPA to your system, update the local repository index and install the lyx package:
$ sudo add-apt-repository ppa:lyx-devel/release
$ sudo apt-get update
$ sudo apt-get install lyx
Optional, to remove lyx, do:
$ sudo apt-get remove lyx
The installation instructions should work on Ubuntu 15.04 Vivid Vervet, Ubuntu 14.04 Trusty Tahr, Ubuntu 12.04 Precise Pangolin and derivative systems like Linux Mint 17.2 Rafaela, Linux Mint 17.1 Rebecca, Linux Mint 17 Qiana, Linux Mint 13 Maya, Pinguy OS 14.04, Elementary OS 0.3 Freya, Elementary OS 0.2 Luna, Deepin 2014, Peppermint 6, Peppermint 5, LXLE 14.04 and Linux Lite 2.