document.write( "Question 697179: jackie mows a uniform width around her 30m by 20m rectangular lawn and leaves a patch of lawn that is 60% of the original area what is the width of the strip \n" ); document.write( "

Algebra.Com's Answer #429740 by josmiceli(19441) $\"\"$ $\"About$

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The original area is $\"+30%2A20+=+600+\"$ m^2
\n" ); document.write( "The area of patch left is $\"+.6%2A600+=+360+\"$
\n" ); document.write( "Let $\"+x+\"$ = the uniform width of mowed part
\n" ); document.write( "The unmowed patch is $\"+30+-+2x+\"$ by $\"+20+-+2x+\"$
\n" ); document.write( " $\"+%28+30+-+2x+%29%2A%28+20+-+2x+%29+=+360+\"$
\n" ); document.write( " $\"+600+-+40x+-+60x+%2B+4x%5E2+=+360+\"$
\n" ); document.write( " $\"+4x%5E2+-+100x+%2B+240+=+0+\"$
\n" ); document.write( " $\"+x%5E2+-+25x+%2B+60+=+0+\"$
\n" ); document.write( "Use quadratic formula
\n" ); document.write( " $\"+x+=+%28-b+%2B-+sqrt%28+b%5E2+-+4%2Aa%2Ac+%29%29+%2F+%282%2Aa%29+\"$
\n" ); document.write( " $\"+a+=+1+\"$
\n" ); document.write( " $\"+b+=+-25+\"$
\n" ); document.write( " $\"+c+=+60+\"$
\n" ); document.write( " $\"+x+=+%28-%28-25%29+%2B-+sqrt%28+%28-25%29%5E2+-+4%2A1%2A60+%29%29+%2F+%282%2A1%29+\"$
\n" ); document.write( " $\"+x+=+%28+25+%2B-+sqrt%28+625+-+240+%29%29+%2F+2+\"$
\n" ); document.write( " $\"+x+=+%28+25+%2B-+sqrt%28+385+%29%29+%2F+2+\"$
\n" ); document.write( " $\"+x+=+%28+25+%2B-+19.6214%29+%2F+2+\"$
\n" ); document.write( " $\"+x+=+5.3786+%2F+2+\"$
\n" ); document.write( " $\"+x+=+2.6893+\"$
\n" ); document.write( "The width of the strip is 2.6893 m
\n" ); document.write( "check answer:
\n" ); document.write( " $\"+%28+30+-+2x+%29%2A%28+20+-+2x+%29+=+360+\"$
\n" ); document.write( " $\"+%28+30+-+5.3786+%29%2A%28+20+-+5.3786+%29+=+360+\"$
\n" ); document.write( " $\"+24.6214+%2A+14.6214+=+360+\"$
\n" ); document.write( " $\"+359.9993+=+360+\"$
\n" ); document.write( "close enough
\n" ); document.write( " \n" ); document.write( "

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