document.write( "Question 36209: Please help! Submitted question earlier didn't get a response.\r
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document.write( "4) Amanda has 400 feet of lumber to frame a rectangular patio (the perimeter of a rectangle is 2 times length plus 2 times width). She wants to maximize the area of her patio (area of a rectangle is length times width). What should the dimensions of the patio be, and show how the maximum area of the patio is calculated from the algebraic equation.\r
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document.write( "Answer:
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Algebra.Com's Answer #22181 by Prithwis(166)![]() ![]() ![]() You can put this solution on YOUR website! Let the length of the rectangular patio be x ft \n" ); document.write( "Perimeter of the rectangular patio = 400 ft \n" ); document.write( "The width of the rectangular patio would be 1/2(400-2x) = 200-x \n" ); document.write( "Area = Length * Width = x(200-x) \n" ); document.write( "We need to maximize f(x) = x(200-x) to achieve the goal of the problem. \n" ); document.write( "f(x) is quadratic function for Area, which represents a parabola opening downward (because the co-efficient of x^2 is negative). \n" ); document.write( "Maximum of f(x) is reached at the vertex (because it opens downward) \n" ); document.write( "x-Coordinate of the vertex = -b/2a (for ax^2+bx+c); \n" ); document.write( "f(x) = -x^2+200x; So, a = -1, b=200, c=0 \n" ); document.write( "(-b/2a) = 100; \n" ); document.write( "So, maximum area can be obtained if the length is 100 feet; \n" ); document.write( "The width will be 1/2(400-200) = 100 feet; \n" ); document.write( "Answer - Dimension of the patio for maximum area will be 100 feet X 100 feet\r \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |