∀ {m : Type u_2} {R : Type u_3} {α : Type u_1} [inst : Fintype m] [inst_1 : DecidableEq m] [inst_2 : CommSemiring R]
  [inst_3 : Semiring α] [inst_4 : Algebra R α] (x : R),
  MulOpposite.unop (RingEquiv.mopMatrix.toFun ((algebraMap R (Matrix m m αᵐᵒᵖ)) x)) =
    MulOpposite.unop ((algebraMap R (Matrix m m α)ᵐᵒᵖ) x)