English
The coefficient of C a times p equals a times the coefficient of p: coeff (C a · p) n = a · coeff p n.
Русский
Коэффициент множителя C a на полином p равен a умноженному на коэффициент p: coeff(C a · p) n = a · coeff p n.
LaTeX
$$$\operatorname{coeff}(C a \cdot p) n = a \cdot \operatorname{coeff}(p, n)$$$
Lean4
@[simp]
theorem coeff_C_mul (p : R[X]) : coeff (C a * p) n = a * coeff p n :=
by
rcases p with ⟨p⟩
simp_rw [← monomial_zero_left, ← ofFinsupp_single, ← ofFinsupp_mul, coeff]
exact AddMonoidAlgebra.single_zero_mul_apply p a n