This seems like a lot of effort to write yet another software to render math. Haven't you ever heard of Excel/Maple/MathCAD/Mathematica/MATLAB/Octave/SMATH Studio?
SMath Studio is excellent software and I highly recommend it. Octave is also great.
Many of these softwares are proprietary.
They do not show numeric substitutions.
They do not auto-format your calculations.
Many are not as extensible as handcalcs because they are not a part of the amazing python eco-system <3
Printing to PDF requires you to have a Latex environment installed
on your system and to have a Latex compiler available on your system's PATH variable so Jupyter can execute xelatex on a command line.
Following an installation, you can open up a command line on your system and type xelatex. If the installation was successful and complete, the command will enter you into a Latex prompt instead of generating an error message.
Installation on Windows is easiest by installing the TeX distribution, MiKTeX. After installation, ensure that you allow automatic downloading of required to make operation easiest.
Installation on Mac OS X is easiest by installing MacTeX.
Be sure to read the installation page to prevent/assist with any issues.
$ sudo apt install texlive-latex-extra