Hello everyone,
I wonder if it is possible to graph |x|+|y|=x^2+y^2 function on TI89 Titanium if so can someone please provide me step-by-step instructions because I always get stuck with the "Undefined Variable" error. No matter what I have done I could not manage to solve the problem. Thanks for your contribution.

Module 13 - Implicit Differentiation

Thanks for the reply but I did not understand what to do. On Wolfram Alpha when I enter the variables I can get the graph, but when I enter them in the same format on TI-89 Titanium I get the "Undefined Variable" error. How can I define the variable, which graph mode and which settings should I use? On the other hand when I use implict differentiation I get a graph that is not alike with the graph I get on Wolfram Alpha. I am very confused should TI89 not be able to graph such functions with ease?(BTW I am a high-school student and unfamiliar with implict differentiation)

You need to read the link provided and follow the instructions. They will help you and you don't need to know anything about calculus to do this. Basically what you are going to do is graph this 3-d equation and then only view the xy-plane, which will show you what you are looking for.

I have managed to graph the sample function on the link but I am still unable to graph |x|+|y|=x^2-y^2 any suggestions? When I try to graph it the only thing I see is x axis and y axis

What do you have set for you x and y min/max values?

screenshots ... note that the graph is in a small window.

Attached Thumbnails

   

I have finally managed to graph the equation my mistake was to write the equation z=x^2-y^2=|x|+|y|