document.write( "Question 428043: Find the least amount of material needed to make a square based open box that has a volume of 5000 cubic meters. \n" ); document.write( "
Algebra.Com's Answer #297599 by htmentor(1343)\"\" \"About 
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The box is open, so it will have 5 sides.
\n" ); document.write( "Let a = the side length of the square bottom
\n" ); document.write( "Let h = the height of the box
\n" ); document.write( "We are given the volume of the box = 5000.
\n" ); document.write( "We need to find a formula for the amount of material required for the box.
\n" ); document.write( "The bottom will have area \"a%5E2\"
\n" ); document.write( "Each side will have area \"ah\", and there are 4 of them.
\n" ); document.write( "Thus, the total amount of material will be:
\n" ); document.write( "\"M+=+a%5E2+%2B+4ah\" (1)
\n" ); document.write( "The volume of the box, \"a%5E2h+=+5000\"
\n" ); document.write( "So \"h+=+5000%2Fa%5E2\"
\n" ); document.write( "Substitute this value for h into equation (1):
\n" ); document.write( "\"M+=+a%5E2+%2B+4a%285000%2Fa%5E2%29+=+a%5E2+%2B+20000%2Fa\"
\n" ); document.write( "To minimize M, we take the derivative and set = 0:
\n" ); document.write( "\"0+=+2a+-+20000%2Fa%5E2\"
\n" ); document.write( "Solve for a:
\n" ); document.write( "\"a%5E3+=+10000+-%3E+a+=+21.544\" m
\n" ); document.write( "Therefore \"h+=+5000%2F21.544%5E2+=+10.772\" m\r
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