Question 1207436
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x = side length, in feet, of the original square sheet metal
x > 0


The square of side length x is reduced to side length x-2 when subtracting 1 foot from each side. 
Notice I subtracted two copies of "1 foot" from each dimension.


volume = length*width*height
volume = (x-2)*(x-2)*1
volume = x^2 - 4x + 4


Set this equal to the volume we want to get,
x^2 - 4x + 4 = 4
x^2 - 4x = 0
x(x-4) = 0
x = 0 or x-4 = 0
x = 0 or x = 4


Ignore x = 0 since it doesn't make x > 0 true.
The only possible answer is x = 4.


The original square sheet metal is 4 by 4.
Subtract off 1 ft for each side to get a 2 by 2 square floor of the box when folding up the sides. Each flap is 1 ft tall.
volume = length*width*height = 2*2*1 = 4 cubic feet
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