TI-89 question (graphing x and y)

[SyN65]

Basically I have to graph x and y but the 89 isn't letting me.

x = -y^2

y = x + 20

I'm sure I have to be in a specific mode or something - I tried function and parametric but neither worked and give me the error "Undefined Variable".

Any help would be much appreciated.

 

[MATLABdude]

Welcome to PhysicsForums!

The key point here is that you're graphing FUNCTIONS of x. Your second equation should work all right (just type x+20 for y1 or y2). For more on basic graphing, click on the "Basic Function Graphing" chapter in the TI-89 manual:
http://education.ti.com/guidebooks/graphing/89ti/TI89TitaniumGuidebook_Part2_EN.pdf

As for your second equation, you just need to solve for x as a function of y (remember, you need both the positive and negative branches of the square root).

Good luck!

 

[trautlein]

You want to be in function mode. Listen to the above poster and reply if you still need help : )