Installation QGIS on Ubuntu 14.04 LTS

Terminal Command:
  

sudo gedit /etc/apt/sources.list 

Add this repository below

deb http://qgis.org/debian trusty main 
deb-src http://qgis.org/debian trusty main

Add key server

gpg --keyserver keyserver.ubuntu.com --recv DD45F6C3
gpg --export --armor DD45F6C3 | sudo apt-key add -

Update source list and Install

sudo apt-get update
sudo apt-get install qgis python-qgis