document.write( "Question 1151928: a box with a square base has no top. if 64 cm squared material is used, what is the maximum possible volume for the box? \n" ); document.write( "
Algebra.Com's Answer #773862 by greenestamps(13200)\"\" \"About 
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\n" ); document.write( "Let x be the side of the square base, and let y be the height (depth) of the box.

\n" ); document.write( "We are to maximize the volume, which is

\n" ); document.write( "\"V+=+%28x%5E2%29%28y%29\"

\n" ); document.write( "We need that volume formula to be in a single variable. Use the given information about the amount of material used to make the box (bottom and four sides) to solve for y in terms of x and substitute in the volume formula.

\n" ); document.write( "\"x%5E2%2B4xy+=+64\" [the total area of the base and four sides is 64 square cm]

\n" ); document.write( "\"4xy+=+64-x%5E2\"
\n" ); document.write( "\"y+=+%2864-x%5E2%29%2F%284x%29+=+16%2Fx-x%2F4\"

\n" ); document.write( "\"V+=+%28x%5E2%29%28y%29+=+%28x%5E2%29%2816%2Fx-x%2F4%29+=+16x-x%5E3%2F4\"

\n" ); document.write( "Find the derivative and set it to zero to find the value of x that maximizes the volume.

\n" ); document.write( "\"dV%2Fdx+=+16-3x%5E2%2F4\"

\n" ); document.write( "\"16-3x%5E2%2F4+=+0\"
\n" ); document.write( "\"3x%5E2%2F4+=+16\"
\n" ); document.write( "\"3x%5E2+=+64\"
\n" ); document.write( "\"x%5E2+=+64%2F3\"
\n" ); document.write( "\"x+=+8%2Fsqrt%283%29\"

\n" ); document.write( "Determine y for that value of x:

\n" ); document.write( "

\n" ); document.write( "Determine the maximum volume:

\n" ); document.write( "\"V+=+%28x%5E2%29%28y%29+=+%2864%2F3%29%28%284%2F3%29sqrt%283%29%29+=+%28256%2F9%29sqrt%283%29\"
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