plot3d({6-3*x-2*y,0}, x=-3..3, y=-3..3, axes=normal);with (student):Tripleint(x, z=0..6-3*x-2*y, y=0..1/2*(6-3*x),x=0..2);value(%);Tripleint(x*y, z=0..1/2*(6-6*x-3*y), y=0..2-2*x,x=0..1);value(%);Tripleint(x*y, z=0..1/2*(6-6*x-3*y), x=0..1/2*(2-y),y=0..2);value(%);plot3d({4*(z^2+y^2),4}, z=-3..3, y=-3..3, axes=normal);