document.write( "Question 766489: a rectangular piece of cardboard has an area of 15cm2. By cutting a square 2cm wide on each side from each of the corners and fold up the sides an open box is formed having a volume of 132ml.find the lenght of the original cardboard?
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Algebra.Com's Answer #466953 by josgarithmetic(39617)\"\" \"About 
You can put this solution on YOUR website!
This rectangular board is x by y cm^2, and both lengths are variable.
\n" ); document.write( "The area allows us \"xy=15\" cm^2. Equivalently, \"y=15%2Fx\"\r
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\n" ); document.write( "\n" ); document.write( "Cutting out the corners and folding to make the rectangular space you have height of 2 cm, so \"2%28x-2%2A2%29%28y-2%2A2%29=132\",
\n" ); document.write( "simplifiable to
\n" ); document.write( "\"%28x-4%29%28y-4%29=66\"
\n" ); document.write( "And we earlier found a formula for y relating to x using the initial carboard area....\r
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\n" ); document.write( "\n" ); document.write( "\"%28x-4%29%2815%2Fx-4%29=66\"
\n" ); document.write( "\"x%2A15%2Fx-4x-4%2A15%2Fx%2B16=66\"
\n" ); document.write( "\"15-4x-60%2Fx%2B16=66\"
\n" ); document.write( "\"-4x-60%2Fx=66-31\"
\n" ); document.write( "\"-4x-60%2Fx=35\"
\n" ); document.write( "\"-4x%5E2-60=35x\"
\n" ); document.write( "\"-4x%5E2-35x-60=0\"
\n" ); document.write( "\"highlight%282x%5E2%2B17.5x%2B30=0%29\"
\n" ); document.write( "\"highlight%284x%5E2%2B35x%2B60=0%29\"\r
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\n" ); document.write( "\n" ); document.write( "General solution to quadratic equation:
\n" ); document.write( "\"x=%28-35%2B-sqrt%2835%5E2-4%2A4%2A60%29%29%2F%282%2A4%29\"
\n" ); document.write( "\"x=%28-35%2B-sqrt%28265%29%29%2F8\"
\n" ); document.write( "We want the positive value for x:
\n" ); document.write( "...It's not happening...
\n" ); document.write( "....?\r
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\n" ); document.write( "\n" ); document.write( "CONSIDER:
\n" ); document.write( "Taking out a 2 by 2 square at each corner means 4*(2*2) cm^2 removed. This is 16 cm^2, but you were only given 15 cm^2. The problem is therefore impossible.
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