# Declare x,y,z as variables
x,y,z=var('x,y,z')

# Draw the explicit z=x^2+y^2, for -10<x<10 y -5<y<5 (HIT "RUN" OR MAY+INTRO)
plot3d(x^2+y^2,(x,-10,10), (y,-5,5))

# Now draw the same in implicit form x^2+y^2-z=0, adding -15<z<15 (HIT "RUN" OR MAY+INTRO)
implicit_plot3d(x^2+y^2-z==0,(x,-10,10),(y,-5,5),(z,-15,15))

# Now the implicit x^2-y^2-z^2=0, same limits (HIT "RUN" OR MAY+INTRO)
implicit_plot3d(x^2-y^2-z^2==0,(x,-10,10),(y,-5,5),(z,-15,15))