Theorem: Model.rst_b4 (ECTate/Algebra/EllipticCurve/Model.lean)

State before:
R : Type u
inst✝ : CommRing R
r s t : R
e : Model R
⊢ b4 (rst_iso r s t e) = b4 e + r * (b2 e + 6 * r)
Tactic:
simp only [rst_iso, b2, b4]
State after:
R : Type u
inst✝ : CommRing R
r s t : R
e : Model R
⊢ (e.a1 + 2 * s) * (e.a3 + r * e.a1 + 2 * t) +
      2 * (e.a4 - s * e.a3 + 2 * r * e.a2 - (t + r * s) * e.a1 + 3 * r * r - 2 * s * t) =
    e.a1 * e.a3 + 2 * e.a4 + r * (e.a1 * e.a1 + 4 * e.a2 + 6 * r)

State before:
R : Type u
inst✝ : CommRing R
r s t : R
e : Model R
⊢ (e.a1 + 2 * s) * (e.a3 + r * e.a1 + 2 * t) +
      2 * (e.a4 - s * e.a3 + 2 * r * e.a2 - (t + r * s) * e.a1 + 3 * r * r - 2 * s * t) =
    e.a1 * e.a3 + 2 * e.a4 + r * (e.a1 * e.a1 + 4 * e.a2 + 6 * r)
Tactic:
ring
State after:
no goals