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A rectangle has an area of 315 cm² . If the length is increased by 2 cm and the width isdecreased by 2 cm, the  area would decrease by 21 cm² Find the dimensions of the original rectangle (Round your answer to 3 significant figures where necessary.)​

 Mar 13, 2021
 #1
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l * w = 315         l = 315/w

(l+2)(w-2) = 315 -21 = 294       sub red into this

 

(315/w + 2) (w-2) = 294

    315 - 630/w   + 2w  -4   - 294 = 0

       2w^2 + 17 w - 630 = 0              Quadratic Formula shows   w = 14  cm        then l = 315/14 = 22.5   cm   (originally)

 Mar 13, 2021

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