Theorem: MyRing.neg_zero (LeanInRome/S2_Basics/S02_Proving_Identities_in_Algebraic_Structures.lean)

State before:
R : Type u_1
inst✝ : Ring R
⊢ -0 = 0
Tactic:
apply neg_eq_of_add_eq_zero
State after:
case h
R : Type u_1
inst✝ : Ring R
⊢ 0 + 0 = 0

State before:
case h
R : Type u_1
inst✝ : Ring R
⊢ 0 + 0 = 0
Tactic:
rw [add_zero]
State after:
no goals