theorem powerMean_eq_scaled_lpNorm {ρ : ℝ} (hρ : ρ ≠ 0) {x : Fin J → ℝ}
(hx : ∀ j, 0 ≤ x j) :
powerMean J ρ hρ x = (1 / ↑J : ℝ) ^ (1 / ρ) * lpNorm J ρ x := by
simp only [powerMean, lpNorm]
have habsrw : ∀ j, |x j| ^ ρ = (x j) ^ ρ := fun j => by rw [abs_of_nonneg (hx j)]
simp_rw [habsrw]
rw [mul_rpow (by positivity : (0 : ℝ) ≤ 1 / ↑J)
(Finset.sum_nonneg (fun j _ => rpow_nonneg (hx j) ρ))]Economics extensions for CES formalization: