case ofFinsupp
R : Type u
a b : R
m n✝ : ℕ
inst✝ : Ring R
q : R[X]
n : ℕ
toFinsupp✝ : AddMonoidAlgebra R ℕ
⊢ coeff ({ toFinsupp := toFinsupp✝ } - q) n = coeff { toFinsupp := toFinsupp✝ } n - coeff q n
R : Type u
a b : R
m n✝ : ℕ
inst✝ : Ring R
p q : R[X]
n : ℕ
⊢ coeff (p - q) n = coeff p n - coeff q n
rcases p with ⟨⟩
case ofFinsupp.ofFinsupp
R : Type u
a b : R
m n✝ : ℕ
inst✝ : Ring R
n : ℕ
toFinsupp✝¹ toFinsupp✝ : AddMonoidAlgebra R ℕ
⊢ coeff ({ toFinsupp := toFinsupp✝¹ } - { toFinsupp := toFinsupp✝ }) n =
    coeff { toFinsupp := toFinsupp✝¹ } n - coeff { toFinsupp := toFinsupp✝ } n
case ofFinsupp
R : Type u
a b : R
m n✝ : ℕ
inst✝ : Ring R
q : R[X]
n : ℕ
toFinsupp✝ : AddMonoidAlgebra R ℕ
⊢ coeff ({ toFinsupp := toFinsupp✝ } - q) n = coeff { toFinsupp := toFinsupp✝ } n - coeff q n
rcases q with ⟨⟩
case ofFinsupp.ofFinsupp
R : Type u
a b : R
m n✝ : ℕ
inst✝ : Ring R
n : ℕ
toFinsupp✝¹ toFinsupp✝ : AddMonoidAlgebra R ℕ
⊢ (match (motive := R[X] → ℕ → R) { toFinsupp := toFinsupp✝¹ - toFinsupp✝ } with
      | { toFinsupp := p } => ↑p)
      n =
    (match (motive := R[X] → ℕ → R) { toFinsupp := toFinsupp✝¹ } with
        | { toFinsupp := p } => ↑p)
        n -
      (match (motive := R[X] → ℕ → R) { toFinsupp := toFinsupp✝ } with
        | { toFinsupp := p } => ↑p)
        n
case ofFinsupp.ofFinsupp
R : Type u
a b : R
m n✝ : ℕ
inst✝ : Ring R
n : ℕ
toFinsupp✝¹ toFinsupp✝ : AddMonoidAlgebra R ℕ
⊢ coeff ({ toFinsupp := toFinsupp✝¹ } - { toFinsupp := toFinsupp✝ }) n =
    coeff { toFinsupp := toFinsupp✝¹ } n - coeff { toFinsupp := toFinsupp✝ } n
rw [← ofFinsupp_sub, coeff, coeff, coeff]
no goals
case ofFinsupp.ofFinsupp
R : Type u
a b : R
m n✝ : ℕ
inst✝ : Ring R
n : ℕ
toFinsupp✝¹ toFinsupp✝ : AddMonoidAlgebra R ℕ
⊢ (match (motive := R[X] → ℕ → R) { toFinsupp := toFinsupp✝¹ - toFinsupp✝ } with
      | { toFinsupp := p } => ↑p)
      n =
    (match (motive := R[X] → ℕ → R) { toFinsupp := toFinsupp✝¹ } with
        | { toFinsupp := p } => ↑p)
        n -
      (match (motive := R[X] → ℕ → R) { toFinsupp := toFinsupp✝ } with
        | { toFinsupp := p } => ↑p)
        n
apply Finsupp.sub_apply