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)\"\" \"About 
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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.
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\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
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\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( "\"2x%5E2%2Ah+=+18\"
\n" ); document.write( "h = \"18%2F%282x%5E2%29\"
\n" ); document.write( "h = \"9%2Fx%5E2\"
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\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 \"18%2F%282x%5E2%29\"
\n" ); document.write( "C(x) = 20x^2 + 48x(\"9%2F%28x%5E2%29\")
\n" ); document.write( "Cancel x
\n" ); document.write( "C(x) = 20x^2 + 48(\"9%2Fx\")
\n" ); document.write( "C(x) = 20x^2 + (\"432%2Fx\")
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\n" ); document.write( "\"+graph%28+300%2C+200%2C+-2%2C+4%2C+-100%2C+400%2C+%2820x%5E2%29%2B%28432%2Fx%29+%29+\"
\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
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\n" ); document.write( "find the height
\n" ); document.write( " h = \"9%2F%282.25%5E2%29\"
\n" ); document.write( " h = \"9%2F5.0625\"
\n" ); document.write( " h = 1.78 meters is the height
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\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
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