2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/122509We introduce the concept of a μ-scale invariant operator with respect to unitary transformation in a separable complex Hilbert space. We show that if a nonnegative densely defined symmetric operator is μ-scale invariant for some μ>0, then both the Friedrichs and the Krein-von Neumann extensions are also μ-scale invariant.Mathematical PhysicsSpectral Theory47A63, 47B25, 47B65text