document.write( "Question 712235: Do you think you could help me with this?\r
\n" ); document.write( "\n" ); document.write( "Bricks are delivered to a work site and stacked in rows and columns, forming a rectangular prism. The length of the prism is 1 foot greater than its width, and its height is 2 feet less than its width. Show how to find the dimensions of the prism formed by the bricks, given that its volume is 40 cubic feet.
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Algebra.Com's Answer #437852 by josgarithmetic(39618)\"\" \"About 
You can put this solution on YOUR website!
The unknown being referenced is the width. \r
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\n" ); document.write( "\n" ); document.write( "Let w be width
\n" ); document.write( "Length is w+1
\n" ); document.write( "Height is w-2\r
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\n" ); document.write( "\n" ); document.write( "\"w%28w%2B1%29%28w-2%29=40\"\r
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\n" ); document.write( "\n" ); document.write( "Some steps,
\n" ); document.write( "\"w%28w%5E2%2Bw-2w-2%29-40=0\"
\n" ); document.write( "w(w^2-w-2)-40=0
\n" ); document.write( "\"w%5E3-w%5E2-2w-40=0\"\r
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\n" ); document.write( "\n" ); document.write( "Solving that is faster if you know synthetic division. You would use the idea of the Rational Roots Theorem to find values for w to satisfy the cubic equation. I'd suggest first working with +/-4, +/-5, +/-8, +/-10. When you get just one first root, the next two will be easy.\r
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\n" ); document.write( "\n" ); document.write( "Some further work:
\n" ); document.write( "Good News! I tried some long divisions and found +5 or -5 are not roots, but that +4 is a root. One of the binomials is (w-4). The quotient from this was \"w%5E2%2B3w%2B10\". So this means your polynomial equation is
\n" ); document.write( "\"%28w-4%29%28w%5E2%2B3w%2B10%29=0\", so the quadratic part should be much easier to manage.\r
\n" ); document.write( "\n" ); document.write( "NOTE: The discriminant for that quadratic is -31, so the solution will contain an imaginary part. The only reasonable value for w is 4.
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