document.write( "Question 342278: An open rectangular box with volume 7 m3 has a square base.
\n" ); document.write( "(a) Express the surface area of the box as a function of the length (x) of a side of the base.
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Algebra.Com's Answer #245189 by nyc_function(2741)\"\" \"About 
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volume = length * width * height
\n" ); document.write( "square base ... let length and width = x
\n" ); document.write( "x^2 * height = 7
\n" ); document.write( "height = 7 / x^2\r
\n" ); document.write( "\n" ); document.write( "Surface area (with open top) = bottom + 4 sides\r
\n" ); document.write( "\n" ); document.write( "Surface area = x^2 + 4 * x * height\r
\n" ); document.write( "\n" ); document.write( ". . . we already know height = 7 / x^2, so substute\r
\n" ); document.write( "\n" ); document.write( "Surface area = x^2 + 4x * 7 / x^2
\n" ); document.write( "Surface area = x^2 + 28 / x <=======
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