congr
R : Type u_1
ι : Type u_2
inst✝ : CommSemiring R
i j : ι
r : R
a✝ : Nontrivial R
this : (X j + C r).totalDegree = 1
⊢ (monomial (Finsupp.single j 1 + Finsupp.single i (1 - 1))) 1 + C r * X i =
    (monomial (Finsupp.single j 1)) 1 + C r * (monomial (Finsupp.single i 1)) 1
case e_a.e_a.e_s
R : Type u_1
ι : Type u_2
inst✝ : CommSemiring R
i j : ι
r : R
a✝ : Nontrivial R
this : (X j + C r).totalDegree = 1
⊢ Finsupp.single j 1 + Finsupp.single i (1 - 1) = Finsupp.single j 1