document.write( "Question 258860: You have 500 ft of fencing all rolled up and you want to make a rectangular playground area for your son. What are the dimensions of the largest playground you could build? \n" ); document.write( "
Algebra.Com's Answer #190579 by Fombitz(32388)\"\" \"About 
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\"A=L%2AW\"
\n" ); document.write( "For a rectangle, the perimeter is
\n" ); document.write( "\"P=2%2A%28L%2BW%29=500\"
\n" ); document.write( "\"L%2BW=250\"
\n" ); document.write( "\"L=250-W\"
\n" ); document.write( "Substitute this into the area equation,
\n" ); document.write( "\"A=%28250-W%29W=250W-W%5E2\"
\n" ); document.write( "To find the maximium area, take the derivative and set it to zero.
\n" ); document.write( "\"dA%2FdW=250-2W=0\"
\n" ); document.write( "\"d2A%2Fdw2=-2\" so you know that the value you get is a maximum (2nd derivative test).
\n" ); document.write( "\"250-2W=0\"
\n" ); document.write( "\"+2W=250\"
\n" ); document.write( "\"W=125\"
\n" ); document.write( "\"L=250-W=125\"
\n" ); document.write( "The rectangle with the most area is actually a 125' x 125' square.
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