9514 1404 393
Answer:
6 m
Step-by-step explanation:
Let p represent the length of the perimeter fence. Let x represent the length parallel to the house. Then the width perpendicular to the house is ...
w = (p -x)/2
and the area of the garden is ...
area = length · width
area = x(p -x)/2
For a fixed perimeter length p, this equation describes a parabola that opens downward. Its vertex is on the line of symmetry, halfway between the zeros. The area will be zero when x=0 and when x=p, so the vertex (maximum area) is located at ...
x = (0 +p)/2 . . . . . average of zero values
x = p/2
Here, we have p=12 m, so p/2 = 6 m, and the width is (12 -6)/2 = 3 m.
The length of the maximum-area garden is 6 meters.
_____
Its area is 18 square meters.