SOLUTION: A rectangle is 8 inches and 12 inches long. If the dimensions are increased by the same amount, thereby its area is increased by 69 square inches,by what amount is the side increas
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Question 1127965: A rectangle is 8 inches and 12 inches long. If the dimensions are increased by the same amount, thereby its area is increased by 69 square inches,by what amount is the side increased? Found 2 solutions by josgarithmetic, ikleyn:Answer by josgarithmetic(39617) (Show Source):
You can put this solution on YOUR website! .
A rectangle is 8 inches and 12 inches long. If the dimensions are increased by the same amount,
thereby its area is increased by 69 square inches,by what amount is the side increased?
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The condition says
(8+x)*(12+x) - 8*12 = 69.
FOIL
8*12 + 12x + 8x + x^2 - 8*12 = 69
x^2 + 20x - 69 = 0
Factor left side polynomial
(x + 23)*(x-3) = 0.
The only positive root x= 3 works.
Answer. The sides increased by 3 inches.
Check. (8+3)*(12+3) - 8*12 = 69. ! Correct !
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