Draw surface bound by ellipse in GeoGebra

Question

I want to draw 3D surface in Geogebra given by f(x,y)=x^2+y^2 bounded by 3x^2+5xy+3y^2=4.I tried using polar representation but the surface does not bind with ellipse.

Answer 1

If the goal is to show the portion of the surface z = x² + y² that lies above the set of all points in the (x,y)-plane inside the ellipse 3x² + 5x y + 3y² = 4, then

If(3x² + 5x y + 3y² < 4, x² + y²)

should work, because b(x,y) = 3x² + 5x y + 3y² is a paraboloid opening upward, so the points inside b(x,y) = 4 are just the ones where b(x,y) takes on a value smaller than 4.