rw [norm_mul, IsROrC.norm_natCast]
case h
n i : ℕ
x : ℝ
⊢ ‖(fun x => ↑(Nat.descFactorial n i) * x ^ (n - i)) x‖ ≤ ↑(Nat.descFactorial n i) * (1 + ‖x‖) ^ (n - i)
case h
n i : ℕ
x : ℝ
⊢ ↑(Nat.descFactorial n i) * ‖x ^ (n - i)‖ ≤ ↑(Nat.descFactorial n i) * (1 + ‖x‖) ^ (n - i)