restart: with(plots):
implicitplot(x^2-y^2*(y+1), x=-1..1, y=-1..1,
             grid=[100,100],thickness=2,scaling=constrained);


m:=solve(x^2-y^2*(y+1),y);


a:=plot(Re(m[1](x)),x=-1..1,color=green):
b:=plot(Re(m[2](x)),x=-0.39..0.39,color=red):
c:=plot(Re(m[3](x)),x=-0.39..0.39,color=blue):
display(a,b,c,scaling=constrained,thickness=2);