A hydraulic power system (Stoecker 1971) must provide 300 W of power, where the power is the product of volume flow rate Q m3 /s and the pressure build up Δp Pa. The cost of the hydraulic pump is a function of both the flow rate and pressure buildup.
Convert to a single-variable unconstrained problem and use geometric programming to determine the minimum cost of the pump and the optimum values of Q and Δp