SOLUTION: If the sides of a square are decreased by 3 cm, the area is decreased by 81 cm^2. What were the dimensions of the original square?

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Question 983385: If the sides of a square are decreased by 3 cm, the area is decreased by 81 cm^2. What were the dimensions of the original square?
Answer by macston(5194) About Me  (Show Source):
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S=side of original square
%28S-3cm%29%5E2=S%5E2-81
S%5E2-6S%2B9=S%5E2-81
-6S%2B9=-81
90=6S
15=S ANSWER: Sides of the original square were 15 cm.
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CHECK:
Original Area=S^2=(15cm)^2=225cm^2
New area=(S-3cm)^2=15cm-3cm)^2=(12cm)^2=144cm^2
Original area-New area=81cm^2
225cm^2-144cm^2=81cm^2
81cm^2=81cm^2