\frac{-9 \pm 41}{32}.If these curves are considered over \mathbb{Q}(\sqrt{10}), there is an isomorphism E_1(\mathbb{Q}(\sqrt{10})) \cong E_2(\mathbb{Q}(\sqrt{10})) sending(x,y)\mapsto (\mu^2x,\mu^3y) \ \text{ where }\ \mu = \frac{\sqrt{10}}{2}.
