> plot3d(sqrt(x+y+1)/(x-1),x=-5..5,y=-5..5,axes=boxed);

> plot3d(sqrt(9-x^2-y^2),x=-3..3,y=-3..3);

> plot3d(sqrt(9-x^2-y^2),x=-3..3,y=-3..3,numpoints=2000);

> plot3d(6-3*x-2*y,x=0..5,y=0..5);

> plot3d([2-2*s-2*t,3*t,6*s],s=0..1,t=0..1-s,axes=boxed,labels=["x","y","z"]);

> plot3d(4*x^2+y^2,x=-10..10,y=-10..10);

> plot3d([0.5*r*cos(t),r*sin(t),r^2],r=0..5,t=0..2*Pi);

> plot3d((x^2+3*y^2)*exp(-x^2-y^2),x=-5..5,y=-5..5);

> plot3d(sin(x)+sin(y),x=-5..5,y=-5..5);

> plot3d((sin(x)*sin(y))/(x*y),x=-5..5,y=-5..5);

>