document.write( "Question 1128128: A rectangular storage container with an open top is to have a volume of 18 cubic meters. The length of its base is twice the width. Material for the base costs 10 dollars per square meter. Material for the sides costs 8 dollars per square meter. Find the cost of materials for the cheapest such container.
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Algebra.Com's Answer #744680 by ankor@dixie-net.com(22740)![]() ![]() You can put this solution on YOUR website! A rectangular storage container with an open top is to have a volume of 18 cubic meters. \n" ); document.write( " The length of it's base is twice the width. \n" ); document.write( ": \n" ); document.write( "let x = the width of the base \n" ); document.write( "then \n" ); document.write( "2x = the length of the base \n" ); document.write( "and \n" ); document.write( "h = height of the box \n" ); document.write( ": \n" ); document.write( "2x^2 = the area of the base \n" ); document.write( "2(2xh) = 4xh = area of the two vertical sides \n" ); document.write( "2xh = area of the two other vertical sides \n" ); document.write( "then \n" ); document.write( "4xh + 2xh = 6xh, the area of the 4 vertical sides\r \n" ); document.write( "\n" ); document.write( "The volume equation \n" ); document.write( " \n" ); document.write( "h = \n" ); document.write( "h = \n" ); document.write( ": \n" ); document.write( " Material for the base costs 10 dollars per square meter. \n" ); document.write( " Material for the sides costs 8 dollars per square meter. \n" ); document.write( " Find the cost of materials for the cheapest such container. \n" ); document.write( "Cost equation \n" ); document.write( "C = 10(2x^2) + 8(6xh) \n" ); document.write( "C = 20x^2 + 48xh \n" ); document.write( "Replace h with \n" ); document.write( "C(x) = 20x^2 + 48x( \n" ); document.write( "Cancel x \n" ); document.write( "C(x) = 20x^2 + 48( \n" ); document.write( "C(x) = 20x^2 + ( \n" ); document.write( ": \n" ); document.write( " \n" ); document.write( "minimum cost: \n" ); document.write( " x = 2.25 meters is the width of the base \n" ); document.write( "and \n" ); document.write( "2(2.25) = 4.5 meters is the length of the base \n" ); document.write( ": \n" ); document.write( "find the height \n" ); document.write( " h = \n" ); document.write( " h = \n" ); document.write( " h = 1.78 meters is the height \n" ); document.write( ": \n" ); document.write( "cost of the open box \n" ); document.write( "C = 10(4.5*2.25) + 8(6*2.25*1.78) \n" ); document.write( "C = 10(10.125) + 8(24) \n" ); document.write( "C = 101.25 + 192 \n" ); document.write( "C = $293.25 the min cost for an open box which is: 2.25 by 4.5 by 1.78 m \n" ); document.write( " |