Error in EllipticCurve_from_cubic
These lines of code generate a message "equation must be a polynomial"
Why?
R.<a,b,c>=QQ[]
n=4
F=a/(b+c)+b/(a+c)+c/(a+b)-n
F=F*F.denominator()
E=EllipticCurve_from_cubic(F,morphism=False)