∀ {R : Type u} [inst : CommRing R] (W : WeierstrassCurve R) (C : WeierstrassCurve.VariableChange R),
  (C • W).a₆ = ↑C.u⁻¹ ^ 6 * (W.a₆ + C.r * W.a₄ + C.r ^ 2 * W.a₂ + C.r ^ 3 - C.t * W.a₃ - C.t ^ 2 - C.r * C.t * W.a₁)