with(plots): contourplot(2*x^2+y^2,x=-4..4,y=-4..4,contours=[1,2,3],scaling=CONSTRAINED); 2*x^2+y^2 = c^2; (x/(c/sqrt(2)))^2 + (y/c)^2 = 1; a = c/sqrt(2); b = c; plot3d(2*x^2+y^2,x=-4..4,y=-4..4);