document.write( "Question 371640: When the dimensions of a cube are reduced by 4 inches on each side, the surface area of the new cube is 864 square inches. What were the dimensions of the original cube? \n" ); document.write( "
Algebra.Com's Answer #264780 by ankor@dixie-net.com(22740)\"\" \"About 
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When the dimensions of a cube are reduced by 4 inches on each side,
\n" ); document.write( " the surface area of the new cube is 864 square inches.
\n" ); document.write( " What were the dimensions of the original cube?
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\n" ); document.write( "Let x = length of sides in the original cube
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\n" ); document.write( "Surface area of original cube = 6x^2
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\n" ); document.write( "New cube surface area:
\n" ); document.write( "6(x-4)^2 = 864
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\n" ); document.write( "FOIL (x-4)(x-4)
\n" ); document.write( "6(x^2 - 8x + 16) = 864
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\n" ); document.write( "Divide both sides by 6
\n" ); document.write( "x^2 - 8x + 16 = 144
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\n" ); document.write( "A quadratic equation
\n" ); document.write( "x^2 - 8x + 16 - 144 = 0
\n" ); document.write( "x^2 - 8x - 128 = 0
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\n" ); document.write( "Factors to:
\n" ); document.write( "(x-16)(x+8) = 0
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\n" ); document.write( "positive solution:
\n" ); document.write( "x = 16 inches, side of original cube
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\n" ); document.write( "New cube side will be 12 inches, find the surface area of new cube:
\n" ); document.write( "6(12^2) = 864, confirms our solution \n" ); document.write( "
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