document.write( "Question 333343: Two rectangles have the same area of 480 cm^2.the diffrence between their lengths is 5cm and the diffrence between their widths is 2cm . calculate the dimension of the rectangles \n" ); document.write( "
Algebra.Com's Answer #238910 by ankor@dixie-net.com(22740)\"\" \"About 
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Two rectangles have the same area of 480 cm^2.
\n" ); document.write( "the difference between their lengths is 5cm and the difference between their widths is 2cm.
\n" ); document.write( " calculate the dimension of the rectangles
\n" ); document.write( ":
\n" ); document.write( "Let the dimension of the original rectangle be L, W
\n" ); document.write( "L*W = 480
\n" ); document.write( "L = \"480%2FW\"
\n" ); document.write( ":
\n" ); document.write( "the dimensions of the other rectangle be (L-5), (w+2)
\n" ); document.write( ":
\n" ); document.write( "Areas of the two rectangles are equal
\n" ); document.write( "(L-5)*(W+2) = L*W
\n" ); document.write( "FOIL
\n" ); document.write( "LW + 2L - 5W - 10 = LW
\n" ); document.write( ":
\n" ); document.write( "Subtract LW from both sides
\n" ); document.write( "2L - 5W - 10 = 0
\n" ); document.write( ":
\n" ); document.write( "Replace L with \"480%2FW\"
\n" ); document.write( "2(\"480%2FW\") - 5W - 10 = 0
\n" ); document.write( "\"960%2FW\" - 5W - 10 = 0
\n" ); document.write( ":
\n" ); document.write( "Multiply by W
\n" ); document.write( "960 - 5W^2 - 10W = 0
\n" ); document.write( ";
\n" ); document.write( "a quadratic equation
\n" ); document.write( "-5W^2 - 10w + 960 = 0
\n" ); document.write( ":
\n" ); document.write( "simplify, divide by -5
\n" ); document.write( "W^2 + 2W - 192 = 0
\n" ); document.write( ":
\n" ); document.write( "Find W using the 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( "in this equation: x=w; a=1; b=2; c=-192
\n" ); document.write( "\"w+=+%28-2+%2B-+sqrt%282%5E2-4%2A1%2A-192+%29%29%2F%282%2A1%29+\"
\n" ); document.write( ":
\n" ); document.write( "\"w+=+%28-2+%2B-+sqrt%284+-+%28-768%29+%29%29%2F2+\"
\n" ); document.write( "\"w+=+%28-2+%2B-+sqrt%284+%2B+768+%29%29%2F2+\"
\n" ); document.write( "\"w+=+%28-2+%2B-+sqrt%28772+%29%29%2F2+\"
\n" ); document.write( "two solutions, but we just want the positive solution
\n" ); document.write( "\"w+=+%28-2+%2B+27.785%29%2F2+\"
\n" ); document.write( "w = \"25.785%2F2\"
\n" ); document.write( "w = 12.89 cm, the width of the original rectangle
\n" ); document.write( "then
\n" ); document.write( "\"480%2F12.89\" = 37.24 cm is the original length
\n" ); document.write( "Check area: 12.89*37.24 = 480.02
\n" ); document.write( ":
\n" ); document.write( "The other rectangle
\n" ); document.write( "12.89 + 2 = 14.89 is the width
\n" ); document.write( "37.24 - 5 = 32.24 is the length
\n" ); document.write( "check area: 14.89*32.24 = 480.05, close enough to confirm our solutions
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