Question

One-stray Problem Solving

POSSIBLE POINTS: 5.88
A rectangular playground is to be fenced in using a wall on one side and 210 meters of fencing for the other three sides. The area A(z) in square meters
of the playground is a function of the length z in meters of the side parallel to the wall.
What is the area of the playground when z = 50?
square meters

Answer 1

a) 5000 m²
b) A(x) = x(200 -2x)
c) 0 < x < 100
Explanation:
b) The remaining fence, after the two sides of length x are fenced, is 200-2x. That is the length of the side parallel to the building. The product of the lengths parallel and perpendicular to the building is the area of the playground:
A(x) = x(200 -2x)
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a) A(50) = 50(200 -2·50) = 50·100 = 5000 . . . . m²
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c) The equation makes no sense if either length (x or 200-2x) is negative, so a reasonable domain is (0, 100). For x=0 or x=100, the playground area is zero, so we're not concerned with those cases, either. Those endpoints could be included in the domain if you like.