∀ {X : Type u_2} [inst : TopologicalSpace X] [inst_1 : Zero X] {A : Type u_1} [inst_2 : NonUnitalRing A]
  [inst_3 : StarRing A] [inst_4 : Module ℝ A] (φ : ContinuousMapZero X NNReal →⋆ₙₐ[NNReal] A) (r : ℝ)
  (f : ContinuousMapZero X ℝ),
  φ (r • f).toNNReal - φ (-(r • f)).toNNReal = (MonoidHom.id ℝ) r • (φ f.toNNReal - φ (-f).toNNReal)