document.write( "Question 177927: The Smith's have 160 meters of fencing available to build a rectangular garden. One side of the garden touches a side of the house and doesn't need any bordering. Algebraically find the dimensions that will give the maximum area. \n" ); document.write( "
Algebra.Com's Answer #132945 by Fombitz(32388)\"\" \"About 
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One side of the rectangle is taken up by the house.
\n" ); document.write( "That leaves 3 sides taken up by fencing.
\n" ); document.write( "Let's call that side W for width and the other two sides will be L to use up the fencing.
\n" ); document.write( "1.\"2L%2BW=160\"
\n" ); document.write( "The area of the rectangle will be
\n" ); document.write( "2.\"A=L%2AW\"
\n" ); document.write( "Use eq. 1 and make the area a function of only one variable.
\n" ); document.write( "1.\"2L%2BW=160\"
\n" ); document.write( "\"W=160-2L\"
\n" ); document.write( "2.\"A=L%2AW\"
\n" ); document.write( "\"A=L%2A%28160-2L%29\"
\n" ); document.write( "\"A=-2L%2A2%2B160L\"
\n" ); document.write( "Now we can differentiate with respect to L and set the derivative equal to zero.
\n" ); document.write( "\"dA%2FdL=-4L%2B160=0\"
\n" ); document.write( "\"L=40\"
\n" ); document.write( "Let's plot the graph of area as a function of length to make sure the area is maximum at this point,
\n" ); document.write( "\"+graph%28+300%2C+300%2C+-20%2C+080%2C+-100%2C+4000%2C+-2x%5E2%2B160x%29+\"
\n" ); document.write( "From eq. 1,
\n" ); document.write( "\"W=160-2L\"
\n" ); document.write( "\"W=160-2%2840%29\"
\n" ); document.write( "\"W=80\"
\n" ); document.write( "The area is then,
\n" ); document.write( "\"A=L%2AW=40%2A80=1250\"
\n" ); document.write( "Width of 80 m, length of 40 m, yields a garden of 3200 sq. meters.
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