A Building in the Shape of a Rectangular Box Is

Short Answer

A building in the shape of a rectangular box is to have a volume of 21,000ft³ (see the figure). It is estimated that the annual heating and cooling costs will be $2/square foot for the top, $7/square foot for the front and back, and $3/square foot for the sides. Find the dimensions of the building that will result in a minimal annual heating and cooling cost. What is the minimal annual heating and cooling cost(C)?
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x = __________
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y = __________
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z = __________
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C = __________