Math problem where graphing calculator may slow you down...

[Bunuel66]

Thanks to all and, please accept my apologies for having used a TI. Just to say that I have a bunch of HP calculators, starting from a HP25 for which I have worked all a summer as a kid to be able to buy it (was a f...g amount of money at that time in France), in the crowd there is also a HP34C, probably one of my favorite, a couple of HP28S very powerful but a bit too complex, lot of others, the last one being a HP 39GII. I'm a bit disappointed with the last HP products (that's why I haven't got a Prime) due to buggy software and unconsistencies between modes. I have a HP35s who could be a great product but so much bugs. I want something I can trust. I like also the HP32 who is quite reliable and it is a product you can trust. Then, yes, I'm a HP lover but from the good old time when a calculator was a tool and not a toy.
That said, in France, the question of using HP is a bit theoritical as they just vanished from the shops. TI and Casio rule. I have a slight bias toward Casio for education as I find them more straightforward to use than TI and more tolerant to the various ways kids input data and equations. Still on an educational side I like Geogebra who is really really great and can run on tablets with Android which is way cool for kids.
Professionally I use Scilab and Python on whatever computer I get. But that is another story.
BTW: I'm not a teacher.....