SOLUTION: a box for shipping roofing nails must have a volume of 84 cubic feet. if the box must be 3 feet wide and its height must be 3 feet less then its length,what should the dimensions o

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: a box for shipping roofing nails must have a volume of 84 cubic feet. if the box must be 3 feet wide and its height must be 3 feet less then its length,what should the dimensions o      Log On


   

Question 209082: a box for shipping roofing nails must have a volume of 84 cubic feet. if the box must be 3 feet wide and its height must be 3 feet less then its length,what should the dimensions of the box be?
Answer by RAY100(1637) About Me  (Show Source):
You can put this solution on YOUR website!
Volume =84 = L*W*H = L*(L-3)*(3)= 3L^2 -9L
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3L^2 -9L -84 =0,,,,,divide by 3
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L^2 -3L-28 = 0
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(L-7)(l+4) =0
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L=7,,-4,,,not realistic
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check, L=7,,,,H=7-3=4,,,W=3,,,,,Vol = 7*4*3 =84,,,ok
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