document.write( "Question 371330: A rectangular lawn is 60 ft by 80 ft. How wide a uniform strip must be cut around the edge in order that 1/6 of the grass be left uncut? \n" ); document.write( "
Algebra.Com's Answer #264681 by ankor@dixie-net.com(22740)\"\" \"About 
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A rectangular lawn is 60 ft by 80 ft.
\n" ); document.write( " How wide a uniform strip must be cut around the edge in order that 1/6 of the grass be left uncut?
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\n" ); document.write( "Find the area: 60 * 80 = 4800 sq/ft
\n" ); document.write( "Find 1/6 of the ares: \"1%2F6\" * 4800 = 800 sq/ft
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\n" ); document.write( "Let x = the width of the uniform strip
\n" ); document.write( "then
\n" ); document.write( "(60-2x) by (80-2x) will be dimensions of the uncut portion
\n" ); document.write( ":
\n" ); document.write( "An area equation
\n" ); document.write( "(60-2x) * (80-2x) = 800
\n" ); document.write( "FOIL
\n" ); document.write( " 4800 - 120x - 160x + 4x^2 = 800
\n" ); document.write( "Arrange as a quadratic equation
\n" ); document.write( "4x^2 - 280x + 4800 - 800 = 0
\n" ); document.write( "4x^2 - 280x + 4000 = 0
\n" ); document.write( "Simplify, divide by 4
\n" ); document.write( "x^2 - 70x + 1000 = 0
\n" ); document.write( "Factors to
\n" ); document.write( "(x-20)(x-50) = 0
\n" ); document.write( "Two solutions
\n" ); document.write( "x = 50
\n" ); document.write( "and
\n" ); document.write( "x = 20 ft is the width of the strip. (this is the only reasonable solution)
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\n" ); document.write( ":
\n" ); document.write( "Check by finding the area
\n" ); document.write( "(60-40) * (80-40) =
\n" ); document.write( "20 * 40 = 800 \n" ); document.write( "
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