document.write( "Question 1187206: the dimension of rectangular metal box are 3cm 5cm and 8 cm. if the first 2 dimension are increased by the same numbers of centimeters, while the 3rd dimension remains the same, the new volume is 34cmcube more than the original volume. what is the new dimension of the enlarged rectangular metal box?
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Algebra.Com's Answer #818150 by math_tutor2020(3817)\"\" \"About 
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\n" ); document.write( "x = amount we increase the first two dimensions by
\n" ); document.write( "The x is a placeholder for some positive number
\n" ); document.write( "The old box is 3 by 5 by 8
\n" ); document.write( "The new box is (3+x) by (5+x) by 8\r
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\n" ); document.write( "\n" ); document.write( "The old volume was
\n" ); document.write( "V1 = 3*5*8 = 120 cm^3\r
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\n" ); document.write( "\n" ); document.write( "The new volume is
\n" ); document.write( "V2 = (3+x)*(5+x)*8
\n" ); document.write( "V2 = (15+3x+5x+x^2)*8
\n" ); document.write( "V2 = 8(x^2+8x+15)
\n" ); document.write( "V2 = 8x^2+64x+120\r
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\n" ); document.write( "\n" ); document.write( "This new volume (V2) is 34 cm^3 larger compared to the old volume (V1)\r
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\n" ); document.write( "\n" ); document.write( "V2 = V1 + 34
\n" ); document.write( "8x^2+64x+120 = 120 + 34
\n" ); document.write( "8x^2+64x+120 = 154
\n" ); document.write( "8x^2+64x+120-154 = 0
\n" ); document.write( "8x^2+64x-34 = 0
\n" ); document.write( "2(4x^2+32x-17) = 0
\n" ); document.write( "4x^2+32x-17 = 0\r
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\n" ); document.write( "\n" ); document.write( "Use factoring or the quadratic formula to find the two possible solutions are:
\n" ); document.write( "x = -17/2 or x = 1/2
\n" ); document.write( "Ignore the first solution. Negative lengths are not possible.\r
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\n" ); document.write( "\n" ); document.write( "The only practical solution is that we increased the first two dimensions by 1/2 = 0.5 cm\r
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\n" ); document.write( "\n" ); document.write( "The first two dimensions of 3 cm and 5 cm become 3.5 cm and 5.5 cm\r
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\n" ); document.write( "\n" ); document.write( "Old Box = 3 cm by 5 cm by 8 cm
\n" ); document.write( "New Box = 3.5 cm by 5.5 cm by 8 cm
\n" ); document.write( "Old volume = 3*5*8 = 120
\n" ); document.write( "New volume = 3.5*5.5*8 = 154
\n" ); document.write( "Difference in volumes = 154-120 = 34
\n" ); document.write( "The answer is confirmed.\r
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\n" ); document.write( "\n" ); document.write( "Answer: 3.5 cm by 5.5 cm by 8 cm
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