document.write( "Question 1099943: A box is constructed out of two different types of metal. The metal for the top and bottom, which are both square, costs $5 per square foot and the metal for the sides costs $2 per square foot. Find the dimensions that minimize cost if the box has a volume of 15 cubic feet. \n" ); document.write( "
Algebra.Com's Answer #714545 by ankor@dixie-net.com(22740) You can put this solution on YOUR website! A box is constructed out of two different types of metal. \n" ); document.write( " The metal for the top and bottom, which are both square, costs $5 per square foot and the metal for the sides costs $2 per square foot. \n" ); document.write( " Find the dimensions that minimize cost if the box has a volume of 15 cubic feet. \n" ); document.write( ": \n" ); document.write( "let s = one side of the square base \n" ); document.write( "let h = the height of the box \n" ); document.write( "then \n" ); document.write( "s^2 * h = 15 cu/ft \n" ); document.write( "Therefore \n" ); document.write( "h = \n" ); document.write( ": \n" ); document.write( "surface area = top, bottom, 4 side areas \n" ); document.write( "SA = 2s^2 + 4hs \n" ); document.write( "replace h with \n" ); document.write( "SA = 2s^2 + 4s* \n" ); document.write( "cancel the s \n" ); document.write( "SA = 2s^2 + (60/s) \n" ); document.write( "Cost of the box \n" ); document.write( "C(x) = 5(2x^2) + 2(60/s) \n" ); document.write( "C(x) = 10x^2 + \n" ); document.write( ": \n" ); document.write( "Graphically, y axis = the cost \n" ); document.write( " \n" ); document.write( "minimum cost when x=1.9 ft \n" ); document.write( "find the height \n" ); document.write( "h = \n" ); document.write( "h = 4.155 ft \n" ); document.write( ": \n" ); document.write( "The dimensions for minimum cost: 1.9 by 1.9 by 4.155 ft Cost about $99.26 (green) \n" ); document.write( " \n" ); document.write( " \n" ); document.write( " |