document.write( "Question 1010811: If a company makes a block of cheese designed to have the height exactly five times the width and the ideal of 1800mm^3 using the least possible surface area, what would be the length \n" ); document.write( "
Algebra.Com's Answer #626273 by josgarithmetic(39630)\"\" \"About 
You can put this solution on YOUR website!
Most of the way through, but short of complete finish:\r
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\n" ); document.write( "\n" ); document.write( "y, height
\n" ); document.write( "x, length
\n" ); document.write( "z, width\r
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\n" ); document.write( "\n" ); document.write( "The description gives from these chosen variables,
\n" ); document.write( "\"system%28y=5z%2Cxyz=1800%29\"
\n" ); document.write( "and the area function you want, depending on name you choose,
\n" ); document.write( "\"A=2xy%2B2yz%2B2xz\".\r
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\n" ); document.write( "\n" ); document.write( "Substitutions to put A as a function of just one single variable...
\n" ); document.write( "\"x%285z%29z=1800\"
\n" ); document.write( "\"5xz%5E2=1800\"
\n" ); document.write( "but z is width, and the question asks for LENGTH to minimize area.
\n" ); document.write( "Try again...
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\n" ); document.write( "\"z=y%2F5\"
\n" ); document.write( "Use in the volume,
\n" ); document.write( "\"xy%28y%2F5%29=1800\"
\n" ); document.write( "still giving a square for what we want to substitute.
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\n" ); document.write( "\n" ); document.write( "Try first aiming for one of the other variables for the single variable in A.
\n" ); document.write( "Go back to description, and substitute for y in A.
\n" ); document.write( "\"A=2x%285z%29%2B2%2A5zz%2B2xz\"
\n" ); document.write( "\"A=10xz%2B10z%5E2%2B2xz\"
\n" ); document.write( "\"A=12xz%2Bz%5E2\"-------want to eliminate, subst for x or z...\r
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\n" ); document.write( "\n" ); document.write( "Look again at description.
\n" ); document.write( "\"x%285z%29z=1800\"
\n" ); document.write( "\"5xz%5E2=1800\"
\n" ); document.write( "\"x=1800%2F%285z%5E2%29=360%2Fz%5E2\"------Substitute for x in A.\r
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\n" ); document.write( "\n" ); document.write( "\"A=12%28360%2Fz%5E2%29z%2Bz%5E2\"
\n" ); document.write( "\"highlight%28A=4320%2Fz%2Bz%5E2%29\"-------Variable z must be used, take derivative, and find what makes A the minimum, and then find the corresponding x value, the asked for length.\r
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\n" ); document.write( "\n" ); document.write( "---------
\n" ); document.write( "continuing,\r
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\n" ); document.write( "\n" ); document.write( "\"A=4320%2Fz%2Bz%5E2\"\r
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\n" ); document.write( "\n" ); document.write( "\"dA%2Fdz=2z-4320%2Fz%5E2\" You fill in the steps to that.\r
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\n" ); document.write( "\n" ); document.write( "Set deriv to 0.
\n" ); document.write( "\"2z%28z%5E2%29%2Fz%5E2-4320%2Fz%5E2=0\"
\n" ); document.write( "\"%282z%5E3-4320%29%2Fz%5E2=0\"
\n" ); document.write( "The denominator does not take meaning here ...
\n" ); document.write( "\"2z%5E3-4320=0\"
\n" ); document.write( "\"z%5E3-2160=0\"
\n" ); document.write( "\"z%5E3=2160\"
\n" ); document.write( "and you can fill-in the steps...
\n" ); document.write( "\"highlight%28z=6sqrt%2810%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "Again use the equations from the description to reach the corresponding value for x, the length.
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