# Plotting a line

I have

x,y = var('x y')

f = (2*x + 3*y == 0)

How do I plot it

plot(f) gives the error:

Traceback (click to the left of this block for traceback) ... ValueError: Variable 'y' not found

And since it complained about y, why didn't it complain about x? Also, where would I find the docs for this question?

And yes, I am a beginner at sage