Solution
= Solution
For a short Weierstrass equation $E:y^2=x^3+ax+b$ in characteristic different from two, the <invariant differential on an elliptic curve>
$$
\omega=\frac{dx}{2y}
$$
is nonzero and regular, including at $O$.
= Solution
For a short Weierstrass equation $E:y^2=x^3+ax+b$ in characteristic different from two, the <invariant differential on an elliptic curve>
$$
\omega=\frac{dx}{2y}
$$
is nonzero and regular, including at $O$.