document.write( "Question 1184802: Among all pairs of numbers whose sum is 16.8, find a pair whose product is as large as possible. What is the maximum​ product?
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Algebra.Com's Answer #815436 by math_helper(2461)\"\" \"About 
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document.write( "For x + u = N, the maximum product xy is \"%28N%2F2%29%5E2\"\r
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document.write( "So  \"+%2816.8%2F2%29%5E2+\" will be the max product.\r
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document.write( "Derivation:
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document.write( "x + y = N --->  y = N-x\r
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document.write( "Now product p is:
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document.write( "\"+p+=+xy+=+x%28N-x%29+=+Nx+-+x%5E2+\"\r
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document.write( "\"+dp%2Fdx+=+N-2x+\"
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document.write( "\"+N-2x+=+0+\"  --->  x = N/2  \r
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document.write( "This is a local MAX value b/c \"+d%5E2p%2Fdx%5E2+=+-2+\" which is concave DOWN.\r
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