@SamR its called desmos... it can do much more than std graphs.... if you get it check the examples. I also love my large button scientific calc and use it on tests.

 

Cool.. I see its available on windows ( via an android app player).... Thanks for that @Wolframore

 

I use this http://www.wiris.net/uoc.edu/wiris/ca/

 

TI-nspire

 

If not Mathematica: SMath Studio?
https://en.smath.com/view/SMathStudio/summary

 

I bought my Son a TI-nspire because he was taking a lot of math and physics. Bought a TI-89 for my Daughter because she was working on an AA degree while she was in high school. I have a TI-86 (bought it decades after I was out of college).

When I was in college, I rented a 4 banger (+,-,x,/) plus sum of squares for polar to rectangular conversions. One of my physics classmates had an HP-45 (cost about $400). He could solve 3 by 3 matrices faster than the teacher's programmable calculator.

When I was a tech, I bought an HP-41C just to have one, but it couldn't graph. I was the only one in our lab with one because there was a 6 month waiting list. My serial number was under 100 (a life test unit) that I got from someone who worked in Corvallis (where they made them).