How to install sympy for Python 3.4

You can use pip3 (which is just normal pip but in system's Python3 packages). Normally I would suggest avoiding using pip for installing stuff globally but given there are no packages for this that could overwrite the files, there's nothing to lose.

It's quick and simple:

sudo apt-get install python3-pip
sudo pip3 install sympy

In Ubuntu 16.04 and later, Sympy Computer Algebra System in Python can be installed from the default Ubuntu repositories. Open the terminal and type:

sudo apt install python3-sympy  

To install Sympy for Python 2.x run:

sudo apt install python-sympy

There's a backports and a nightly PPA with versions for all recent Ubuntu releases. Simply go

sudo add-apt-repository ppa:nschloe/sympy-backports
sudo apt update
sudo apt install python3-sympy