English
If f grows polynomially and is nonnegative eventually, then f^p grows polynomially for any natural p.
Русский
Если f растёт полиномиально и неотрицательна в бесконечности, то f^p растёт полиномиально для любого натурального p.
LaTeX
$$$\\text{GrowsPolynomially}(f) \\land (\\forall^\\infty x, 0 \\le f(x)) \\Rightarrow \\text{GrowsPolynomially}(x \\mapsto f(x)^{p})\\text{ for }p\\in\\mathbb{N}$$$
Lean4
protected theorem pow (p : ℕ) (hf : GrowsPolynomially f) (hf_nonneg : ∀ᶠ x in atTop, 0 ≤ f x) :
GrowsPolynomially fun x => (f x) ^ p := by
simp_rw [← rpow_natCast]
exact hf.rpow p hf_nonneg