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| | |
| | | W
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L
A = LW. ; L + 3W = 120. so L = 120 - 3W
A = (120 - 3W)(W) = -3W2 + 120W
This area function is quadratic in W, meaning it will graph as a concave down parabola with a vertex at W = -b/2a = 20. L = 120 - 3(20) = 60
The ideal dimensions are 20 x 60 m , which will enclose the maximum area of 1,200 m2.