Swimming Areas. A summer camp has 240 ft of float line with which to rope off three adjace...

Swimming Areas. A summer camp has 240 ft of float line with which to rope off three adjacent rectangular areas of a lake for swimming lessons, one for each of three levels of swimming ability. A beach forms one side of the swimming areas. Suppose the width of each area is x yards.

a) Express the total area of the three swimming areas as a function of x.

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b) Find the domain of the function.

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c) Using the graph of the function shown below, determine the dimensions that yield the maximum area.