I know how to use ImplicitPlot to plot things such as x^2+y^2==4, but how do I extend this into 3D? I'm trying to work with an equation of the form
a x^2 + b y^2 + c z^2 == d (depending on the values of a,b,c,& d, an elliptical cylinder, a paraboloid, a hyperboloid, or an elliptical cone)
and though Mathematica says there is no ImplicitPlot3D, I have seen graphics of these expressions. How do I produce them?