Monday, July 23, 2012

The length of a rectangular field is 12m more than width.The value of its area= 4 times the value of its perimeter. Find dimensions of the field.

We have to find the length of a rectangular given that the
length is 12m more than the width and the numeric value of the area is four times that
of the perimeter.


Let the length be L adn the width be
W


The perimeter is 2*(L +
W)


The area is L*W


The length
is 12m more than the width, L = W + 12


Area  = W*(W + 12) =
4* 2*(W + 12 + W)


=> W^2 + 12W = 8*(2W +
12)


=> W^2 + 12W = 16W +
96


=> W^2 - 4W - 96 =
0


=> W^2 - 12W + 8W - 96 =
0


=> W(W - 12) + 8(W - 12) =
0


=> W = 12 or -8


The
width cannot be negative, so we take width = 12


The length
= 12 + 12 = 24


The dimensions of the
rectangle are 12m W by 24m L.

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