document.write( "Question 1099767: a) A rectangular pen is build with one side against a barn. If 2100 m of fencing are used for the other three sides of the pen, what dimensions maximize the area of the pen?
\n" ); document.write( "b) A rancher plans to make four identical and adjacent rectangular pens against a barn, each with an area of 400m^2. What are the dimensions of each pen that minimize the amount of fence that must be used?
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Algebra.Com's Answer #714236 by josmiceli(19441)\"\" \"About 
You can put this solution on YOUR website!
(a)
\n" ); document.write( "Let \"+W+\" = the length of the
\n" ); document.write( "side perpendicular to the barn
\n" ); document.write( "\"+2100+-+2W+\" = the length of the side
\n" ); document.write( "parallel to the barn
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\n" ); document.write( "\"+A+=+W%2A%28+2100+-+2W+%29+\"
\n" ); document.write( "\"+A+=+-2W%5E2+%2B+2100W+\"
\n" ); document.write( "The formula for the W-value of the
\n" ); document.write( "maximum is:
\n" ); document.write( "\"+W%5Bmax%5D+=+-b%2F%282a%29+\"
\n" ); document.write( "\"+a+=+-2+\"
\n" ); document.write( "\"+b+=+2100+\"
\n" ); document.write( "\"+W%5Bmax%5D+=+-2100%2F%28+2%2A%28-2%29+%29+\"
\n" ); document.write( "\"+W%5Bmax%5D+=+525+\"
\n" ); document.write( "and
\n" ); document.write( "\"+2100+-+2W+=+2100+-+2%2A525+\"
\n" ); document.write( "\"+2100+-+1050+=+1050+\"
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\n" ); document.write( "The dimensions that maximize area are:
\n" ); document.write( "525 x 1050
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\n" ); document.write( "check:
\n" ); document.write( "\"+A%5Bmax%5D+=+-2%2A%28W%5Bmax%5D%29%5E2+%2B+2100W%5Bmax%5D+\"
\n" ); document.write( "\"+A%5Bmax%5D+=+-2%2A525%5E2+%2B+2100%2A525+\"
\n" ); document.write( "\"+A%5Bmax%5D+=+-551250+%2B+1102500+\"
\n" ); document.write( "\"+A%5Bmax%5D+=+551250+\" m2
\n" ); document.write( "and
\n" ); document.write( "\"+525%2A1050+=+551250+\" m2
\n" ); document.write( "OK\r
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