Mr.Zulkifli is an architect. He is required to prepare a plan for the construction of a swimming pool which is rectangular in shape. Given that the length of the pool is 6 m more than it's width and a lane with 1 my width is built around the pool. If the area of the pool, including the adjacent lane is 72 m^2, find the length of the pool to be built.

2

Jawapan

2015-10-10T22:12:01+08:00
Lenght = 6 + w
Width = w
lane = 2
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(6 + w + 2) x (w + 2) = 72
6w + 12 + w² + 2w + 2w + 4 = 72
                           w² + 10w = 72 - 12 - 4
                           w² + 10 w = 56
                     w² + 10w - 56 = 0
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w² + 10w - 56 = 0
(w - 4) (w + 14)

w - 4 = 0
     w = 4 
w + 14 = 0
        w = -14
_____________________so, width is 4

Lenght = 6 + w
           = 6 + 4 
           = 10m

1 5 1
2015-10-15T00:59:23+08:00
Length = 6m + width
lane = 1m around pool
area = 72 m^2

L = 6 +W

(L +2)(W +2) = 72
(6 +W +2)(W +2) =72
(8 +W)(W +2) -72 = 0
8W +16 +W^2 +2W -72 = 0
W^2 +10W -56 = 0
(W +14)(W -4) = 0

W +14 = 0
W = -14

W -4 = 0
W = 4m (choose this value)

L = 6 +W
L = 6 +4
L = 10m