# EJERCICIO 14:
x,y,z=var('x,y,z')
F=x*y
Gx=x-1
Hx=x+1
Gy=y-1
Hy=y+1
p1=plot3d(F,(x,-3,3),(y,-3,3),color='blue')
p2=implicit_plot3d(Gx==0,(x,-1,1),(y,-1,1),(z,-9,9), color='red')
p3=implicit_plot3d(Hx==0.00001,(x,-1,1),(y,-1,1),(z,-9,9), color='red')
p4=implicit_plot3d(Gy==0,(x,-1,1),(y,-1,1),(z,-9,9), color='red')
p5=implicit_plot3d(Hy==0.00001,(x,-1,1),(y,-1,1),(z,-9,9), color='red')
p1+p2+p3+p4+p5