document.write( "Question 103809: If the sides of a square are decreased by 3 cm, the area is decreased by 81 cm2. What were the dimensions of the original square?
\n" ); document.write( "L - 3 x W - 3 = -81cm2
\n" ); document.write( " +3 +3 = +6
\n" ); document.write( "L x W = -75cm2
\n" ); document.write( "/2 = /2
\n" ); document.write( " L x W = -37.5\r
\n" ); document.write( "\n" ); document.write( "Can someone help me, I keep messing up the formula, please help \n" ); document.write( "

Algebra.Com's Answer #75470 by kev82(151) $\"\"$ $\"About$

You can put this solution on YOUR website!
Firstly, it is a square, so L=W. I'm going to call this length X. The area of it now is $\"X%5E2\"$ , But if we decrease the side lengths it becomes 81 units smaller so the decreased area is $\"X%5E2-81\"$ .\r
\n" ); document.write( "\n" ); document.write( "Both of the dimensions have been decreased by 3 units, so the area after the decrease can also be worked out as $\"%28X-3%29%28X-3%29\"$ .
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\n" ); document.write( "\n" ); document.write( "Both of these expressions gives the same thing (the area after the decrease) so they must be equal, hence:
\r
\n" ); document.write( "\n" ); document.write( " $\"%28X-3%29%28X-3%29=X%5E2-81\"$
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\n" ); document.write( "\n" ); document.write( "See if you ca solve this equation for X.
\r
\n" ); document.write( "\n" ); document.write( "Kev \n" ); document.write( "

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