document.write( "Question 202617: A rectangle is half as wide as it is long. If both the length and width are decreased by 2 cm, the area decreases by 68 cm(squared) . Find the length of the original rectangle. \n" ); document.write( "
Algebra.Com's Answer #152829 by Earlsdon(6294)\"\" \"About 
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Let the original length = L and the original width = W, so that the original area:
\n" ); document.write( "\"A+=+L%2AW\" but the problem says that the \"...rectangle is half as wide as it is long.\", so this can be expressed as:
\n" ); document.write( "\"W+=+%281%2F2%29L\" Substitute this into the first equation and you get:
\n" ); document.write( "\"A+=+%281%2F2%29L%5E2\"
\n" ); document.write( "Now, if we subtract 2 cm from the length (L-2) and 2 cm from the width (W-2) the area is decreased by 68 sq.cm. (A-68). Lets find the new area:
\n" ); document.write( "\"A-68+=+%28L-2%29%28W-2%29\" but substitute \"W+=+%281%2F2%29L\" and \"A+=+%281%2F2%29L%5E2\"
\n" ); document.write( "\"%281%2F2%29L%5E2-68+=+%28L-2%29%28%281%2F2%29L-2%29\" Simplifying:
\n" ); document.write( "\"%281%2F2%29L%5E2-68+=+%281%2F2%29L%5E2-3L%2B4\" Subtract \"1%2F2L%5E2\" from both sides.
\n" ); document.write( "\"-68+=+-3L%2B4\" Subtract 4 from both sides.
\n" ); document.write( "\"-72+=+-3L\" Divide both sides by -3.
\n" ); document.write( "\"L+=+24\" and
\n" ); document.write( "\"W+=+%281%2F2%29L\"
\n" ); document.write( "\"W+=+12\"
\n" ); document.write( "The original length of the rectangle is 24 cm.
\n" ); document.write( "Check:
\n" ); document.write( "Original area:
\n" ); document.write( "\"A%5Bo%5D+=+L%2AW\" Substitute L=24 and W=12
\n" ); document.write( "\"A%5Bo%5D+=+24%2A12\"
\n" ); document.write( "\"A%5Bo%5D+=+288\"sq.cm.
\n" ); document.write( "Now the new area is:
\n" ); document.write( "\"A%5Bn%5D+=+%28L-2%29%28W-2%29\" Substitute L=24 and W=12
\n" ); document.write( "\"A%5Bn%5D+=+%2824-2%29%2812-2%29\"
\n" ); document.write( "\"A%5Bn%5D+=+%2822%29%2810%29\"
\n" ); document.write( "\"A%5Bn%5D+=+220\"sq.cm.
\n" ); document.write( "The difference is:
\n" ); document.write( "\"A%5Bn%5D-A%5Bo%5D+=+288-220\"=\"168\"sq.cm.
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