An inequality for power

Denote the current vector, the voltage vector, and the power dissipated in a resistive reciprocal passive lumped, or distributed, n-port by {i, e, P}, respectively. Consider the two actual, and one hypothetical, regimes {i 1 , e 1 , P 1 }, {i 2 , e 2 , P 2 }, and {i 1 , e 2 , P}. It is shown that P ≤ √P 1 P 2 .