Probem+11+Hannah+N.,+Jana

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the question asked how to get the area of 1.5 million square feet, with getting the lowest price. Clearly that meant use as little fencing as possible, so that is why the fence in the middle of the rectangle is the same distance as with the length, in order get the same area, with less fencing. You have shown that there is a critical value at w= 1500; how do we know that it is the value that will yield the absolute minimum?