have hchar'' : (3 : K) = 0 := by simp [← hchar', ringChar.Nat.cast_ringChar]
K : Type u
inst✝¹ : CommRing K
inst✝ : IsDomain K
e : Model K
h : ringChar K = 3
hchar' : ↑(ringChar K) = 3
⊢ c4 e = 0 ↔ b2 e = 0
K : Type u
inst✝¹ : CommRing K
inst✝ : IsDomain K
e : Model K
h : ringChar K = 3
hchar' : ↑(ringChar K) = 3
hchar'' : 3 = 0
⊢ c4 e = 0 ↔ b2 e = 0