question about calculator

[soccerball3211]

I recently bought a ti-89 titanium and when I try to use the implicit differentiation tool to solve (x^2)-(xy)+(y^2)=7 I get (-x/y). I know that the right answer is (dy/dx)=(y-2x)/(2y-x). Does anyone have an suggestion to what I might be doing wrong. Any help is much appreciated.

 

[stapel]

Try going to the Calculator Questions forum and posting the exact keystrokes you're using. Maybe somebody there can figure it out.

Thank you.

Eliz.