I am trying to obtain a 3D plot of $z=x^2+2y^2$ that is bound by the region in the $z=0$ plane governed by the equations $y=x$ and $y=x^2$. Is it possible to do this with RegionFunction? or RegionPlot3D?


1 Answer 1


This should work, if I understood your question correctly:

  x^2 + 2 y^2,
  {x, y} ∈ ImplicitRegion[x^2 <= y <= x, {x, y}]

3D plot of a slice

  • $\begingroup$ Thanks. That worked perfectly. I am new to this and was not aware of the Implicit Region. $\endgroup$
    – GeorgeE
    Commented Jun 14, 2022 at 16:51
  • $\begingroup$ @GeorgeE Great, glad it helped! If you find my answer useful, you can upvote it for now and, eventually, accept is by clicking on the gray checkmark beside it. $\endgroup$
    – MarcoB
    Commented Jun 14, 2022 at 17:32

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