A fence is to enclose a rectangular area. One side is against a building so it needs no fence. This fencing costs $10/m. Inside the rectangular area there is a another fence at right angles to the building, costing $4/m. The total area enclosed is 12m^2. Find the dimensions for minimum cost. Include a second derivative test to show this is a minimum and include an answer with units and 3 sig. digits.
Im having problems figuring out how to solve this problem. Help would be greatly appreciated. Thanks!