SOLUTION: If the sides of a square are decreased by 3 cm, the area is decreased by 81cm^2. What were the dimensions of the original square? Could someone please help me, this has thrown me o

Question 120535: If the sides of a square are decreased by 3 cm, the area is decreased by 81cm^2. What were the dimensions of the original square? Could someone please help me, this has thrown me off! Thank you so much in advance.
Found 2 solutions by solver91311, josmiceli:
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!
Let s be the side of the original square. Then the area of the original square would be . If you decrease the sides by 3 cm, then the side of the new square would be , and the area of the new square would be . But we know that the new square has less area than the old square, so we can write:

Substituting:

Now, expand the binomial, collect like terms, and solve the result

Add to both sides

Divide by 6

Check the answer:
and . , answer checks.

Hope that helps,
John
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Call the sides of the original square
The area of the original square is
When I decrease the sides by 3 cm, I have an area
of
In words:
81 cm^2 = (original area) - (area reduced by 3cm on each side)

The original square is 15 cm x 15 cm

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