For the function
g(x,y) = (x+y)/(x-y)
I found that the domain is all (x,y) such that x is different from y.
Then I had to find the level curves, but for c = -1, I get x = 0
But that is not a function, so what does this mean? Does it mean that the image of this function will never be minus one? But I plotted it, and the value minus one is reached, so I don't understand what happens when
(x+y) / (x-y) = -1
and I would like to know if c = -1 is a level curve or not. Thanks!