English
For any f ∈ R[X], the nth coefficient of reverse f equals the coefficient of f at revAt(n, natDegree f): coeff(reverse f, n) = coeff(f, revAt(n, natDegree f)).
Русский
Для любого f ∈ R[X] коэффициент степени n в reverse f равен коэффициенту f на индексе revAt(n, natDegree f): coeff(reverse f, n) = coeff(f, revAt(n, natDegree f)).
LaTeX
$$$\operatorname{coeff}(\operatorname{reverse}(f), n) = \operatorname{coeff}\left(f, \operatorname{revAt}(\operatorname{natDegree}(f), n)\right).$$$
Lean4
theorem coeff_reverse (f : R[X]) (n : ℕ) : f.reverse.coeff n = f.coeff (revAt f.natDegree n) := by
rw [reverse, coeff_reflect]