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The average depth of our rectangular swimming pool is 2 meters. If the pool
holds 520 m3 of water, and the length of one side is 6 meters less than twice
the length of the other side, what are the dimensions of our swimming pool?
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Let w be the width, in meters;
then (2w-6) meters is the length, according to the condition.
The equation for the volume is
2*w*(2w-6) = 520.
Simplify ir step by step
w*(2w-6) = 520/2 = 260
w*(w-3) = 130.
At this point, the solution is OBVIOUS: w = 13 meters.
You can get it algebraically, too
w^2 - 3w - 130 = 0
(w-13)*(w+10) = 0
The only positive root w= 13 is the solution.
ANSWER. The width is 13 meters; the length is 2*13-6 = 26-6 = 20 meters.
Solved.