English
For p ∈ R[X] and n ∈ ℕ, smeval of (X^n · p) equals x^n times smeval of p: (X^n · p).smeval x = x^n · p.smeval x.
Русский
Для p ∈ R[X] и n ∈ ℕ, smeval (X^n · p) = x^n · p.smeval x.
LaTeX
$$$$ (X^n \cdot p).smeval x = x^n \cdot p.smeval x. $$$$
Lean4
theorem smeval_monomial_mul (n : ℕ) : (monomial n r * p).smeval x = r • (x ^ n * p.smeval x) := by
induction p using Polynomial.induction_on' with
| add r s hr hs =>
simp only [smeval_add]
rw [← C_mul_X_pow_eq_monomial, mul_assoc, smeval_C_mul, smeval_X_pow_mul, smeval_add]
| monomial n a => rw [smeval_monomial, monomial_mul_monomial, smeval_monomial, npow_add, mul_smul, mul_smul_comm]