1829.sagews

var('x, y')
plot3d(x^2*y/(x^4+y^2), (x,-1,1), (y,-1,1), plot_points = [200,200])+ text3d("z=x^2y/(x^4+y^2)",(1/2,1/2,1))

var('x, y')
a=0.000001
plot3d(x^(1/3)*y^(1/3), (x,a,1), (y,a,1))+plot3d(-abs(x)^(1/3)*y^(1/3), (x,-1,-a), (y,a,1))+plot3d(-abs(x)^(1/3)*abs(y)^(1/3), (x,a,1), (y,-1,-a))+plot3d(abs(x)^(1/3)*abs(y)^(1/3), (x,-1,-a), (y,-1,-a))+text3d("x^(1/3)y^(1/3)",(1/2,1/2,1))