document.write( "Question 1051181: Please help me how to solve this problem.Thanks.\r
\n" );
document.write( "\n" );
document.write( "Ramon wants to fence in a rectangular portion of his back yard against the back of his garage for a vegetable garden. He plans to use 68 feet of fence, and needs fence on only three sides. Find the maximum area he can enclose. (Hint: The lengths of the 3 fenced sides of the rectangle must add up to 68.) \n" );
document.write( "
Algebra.Com's Answer #666756 by rothauserc(4718)![]() ![]() You can put this solution on YOUR website! we know that \n" ); document.write( ": \n" ); document.write( "1) l + 2w = 68, where l is the length and w is the width of the rectangle \n" ); document.write( ": \n" ); document.write( "also \n" ); document.write( ": \n" ); document.write( "2) l * w = Area of the rectangle \n" ); document.write( ": \n" ); document.write( "solve equation 1) for l \n" ); document.write( ": \n" ); document.write( "l = 68 - 2w \n" ); document.write( ": \n" ); document.write( "substitute for l in equation 2) \n" ); document.write( ": \n" ); document.write( "w * (68 - 2w) = Area \n" ); document.write( ": \n" ); document.write( "-2w^2 + 68w = Area \n" ); document.write( ": \n" ); document.write( "The equation for the Area in terms of w is a parabola that opens downward, so \n" ); document.write( "we know that w is maximum at the vertex \n" ); document.write( ": \n" ); document.write( "To find w, we take the first derivative of the equation for Area, then set it \n" ); document.write( "equal to 0 and solve for w \n" ); document.write( ": \n" ); document.write( "-4w + 68 = 0 \n" ); document.write( ": \n" ); document.write( "-4w = -68 \n" ); document.write( ": \n" ); document.write( "w = 17 \n" ); document.write( ": \n" ); document.write( "l = 68 -2(17) = 34 \n" ); document.write( ": \n" ); document.write( "***************************************** \n" ); document.write( "Maximum Area is 34 * 17 = 578 square feet \n" ); document.write( "***************************************** \n" ); document.write( ":\r \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |