QR Codes & Math

I am ready to do more with QR codes to use with my Algebra students, but I have hit a wall.  How do you create a QR code that displays one math equation or expression that contains exponents and other math symbols?

I have come across some ways to create QR codes - different apps and websites, and also using Google docs.  Today I came across Tammy Worcester's blog that explains how to create QR codes using Google docs - specifically using a spreadsheet.  I thought, "Here it is!  Here is the place where I will be able to create text for a QR code with math symbols."

Here is what my test run spreadsheet looked like:

It didn't work as I had hoped.  Bummer.  When I scanned the top QR Code, the word "hello" showed up without a problem.  When I scanned the bottom QR Code, this is what I saw:

Not only can you not do exponents in the actual spreadsheet, but the PLUS sign doesn't not show up when scanned.

So, I am back to the drawing board and will continue my search to integrate math with QR codes.  If anyone out there has any ideas or thoughts on this issue, I would love to hear from you.