document.write( "Question 157330: If the sides of a square are lengthened by 5cm, the area becomes 81cm^2. Find the length of a side of the original square. \n" ); document.write( "

Algebra.Com's Answer #115956 by jojo14344(1513) $\"\"$ $\"About$

You can put this solution on YOUR website!
Let $\"s\"$ = original side
\n" ); document.write( " $\"s%2B5\"$ = lengthened by 5 cm
\n" ); document.write( " $\"A%5Bnew%5D=81cm%5E2\"$
\n" ); document.write( "So, $\"A%5Bnew%5D=%28s%2B5%29%5E2\"$ ---------------> working eqn
\n" ); document.write( " $\"81=s%5E2%2B10s%2B25\"$
\n" ); document.write( " $\"s%5E2%2B10s%2B25-81=0\"$
\n" ); document.write( " $\"s%5E2%2B10s-56=0\"$ , factor out, perfect square
\n" ); document.write( " $\"%28s%2B14%29%28s-4%29=0\"$
\n" ); document.write( "2 values: $\"s=-14\"$ ----------> don't use
\n" ); document.write( " $\"s=4cm\"$ ---------------------> original side
\n" ); document.write( "In doubt? go back working eqn,
\n" ); document.write( " $\"81=%28s%2B5%29%5E2\"$
\n" ); document.write( " $\"81=%284%2B5%29%5E2\"$
\n" ); document.write( " $\"81=9%5E2\"$
\n" ); document.write( " $\"81=81\"$
\n" ); document.write( "thank you,
\n" ); document.write( "Jojo \n" ); document.write( "

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