simp only [add_right_eq_self, Finsupp.single_eq_same, tsub_eq_zero_iff_le, Finsupp.single_tsub,
  Finsupp.single_le_iff]
R : Type u_1
ι : Type u_2
inst✝ : CommSemiring R
i : ι
p : MvPolynomial ι R
hpn : ¬p = 0
hp : IsWeightedHomogeneous 1 p p.totalDegree
x : ι →₀ ℕ
hx : x ∈ p.support
⊢ (fun j => j + Finsupp.single i (p.totalDegree - j.sum fun _x m => m)) x = x
R : Type u_1
ι : Type u_2
inst✝ : CommSemiring R
i : ι
p : MvPolynomial ι R
hpn : ¬p = 0
hp : IsWeightedHomogeneous 1 p p.totalDegree
x : ι →₀ ℕ
hx : x ∈ p.support
⊢ p.totalDegree ≤ x.sum fun _x m => m