Derivating problems

[Han]

(08-22-2018 05:53 PM)kjpuma Wrote:  Hi world, I'm starting using this hp prime v2. But, I've got a problem with this when trying to get partial derivatives or just one variable-derivative.
For example: when I type "diff(x^2-6*xy^2+y^2+10*y+18,X)", it just shows: 2x, taking Y as 0, what I want is to know what is wrong with my calculator or some settings I've chosen before.

There are several problems with your command.

1. xy is different from x*y -- always be explicit with your operators as no software will be able to tell the difference between the mathematical product \( xy \) from the variable name \( xy \) without explicit operators.

2. You used a mixture of 'x' and 'X' for your variables. They are necessarily different. Moreover, the 'X' variable is a system variable whose content is always a real number (which may cause issues with symbolic manipulation).

3. Make sure you are using the CAS view and make sure that nothing is stored in the variables you are using. In your case, if you stick to using 'x' and 'y' (lowercase) then you can "delete" them using: purge([x,y]) in the CAS view.