document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=165454>Question 165454</A>: <I><SPAN STYLE=\"word-break: break-all;\"> This is a math stars question I can't don't know how to tell my son how to get the answer.<BR>\n" );
document.write( "Faye has 20 feet of fencing to make a rectangular pen for her dog. what is the largest area that she can fence in? His teacher said answer is 25 square feet-how did she get that answer? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #121939 by </B><A HREF=/tutors/aboutme.mpl?userid=Alan3354><B>Alan3354(69443)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Alan3354><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=Alan3354><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=121939\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> This is a math stars question I can't don't know how to tell my son how to get the answer.<BR>\n" );
document.write( "Faye has 20 feet of fencing to make a rectangular pen for her dog. what is the largest area that she can fence in? His teacher said answer is 25 square feet-how did she get that answer?<BR>\n" );
document.write( "-------------------------<BR>\n" );
document.write( "L = length<BR>\n" );
document.write( "W = width<BR>\n" );
document.write( "2L + 2W = 20, L + W = 10, or W = 10 - L<BR>\n" );
document.write( "Area = L*W = L*(10-L)<BR>\n" );
document.write( "A = 10L - L^2<BR>\n" );
document.write( "For maximum, set the 1st derivative equal to zero.<BR>\n" );
document.write( "10 - 2L = 0<BR>\n" );
document.write( "L = 5 (for max area)<BR>\n" );
document.write( "W is also 5, so the max area is 25 sq ft.\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );