right (0,0,0) is the vertex of the cone. And {x<0} is another branch of the second cone.
While for the first one only the {x>0} branch is allowed.
Why is that,
Is a single cone while,
consists of 2 cones, tip to tip?
I know that the second surface consists of elliptical cones, but I don't see how that could make any difference.
How come for,
my solutions manual only shows one cone? Couldn't I rewrite this as,
Certainly there are negative values of x that will satisfy this equation as well, right?