document.write( "Question 869356: the perimeter of a rectangle and square are 160 metre each. the area of rectangle is less than that of square by 100 square metre. find the length of rectangle?
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Algebra.Com's Answer #524143 by josgarithmetic(39617)\"\" \"About 
You can put this solution on YOUR website!
Assign variables.
\n" ); document.write( "s = length of square
\n" ); document.write( "x = rectangle length
\n" ); document.write( "y = rectangle width
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\n" ); document.write( "Find equations and expressions.
\n" ); document.write( "\"4s=160\".
\n" ); document.write( "\"2%28x%2By%29=160\".
\n" ); document.write( "Area of square, \"s%5E2\".
\n" ); document.write( "Area of rectangle, \"xy\".
\n" ); document.write( "\"s%5E2-xy=100\".\r
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\n" ); document.write( "\n" ); document.write( "SYSTEM OF EQUATIONS:
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\n" ); document.write( "4s=160
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\n" ); document.write( "2x+2y=160
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\n" ); document.write( "s^2-xy=100
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\n" ); document.write( "\n" ); document.write( "The question is to find length of the rectangle. No distinction is necessary about x or y for length; either one is length or width. First, solve for s and obtain two equations in two unknowns.\r
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\n" ); document.write( "\n" ); document.write( "\"s=160%2F4\", \"s=40\".
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\n" ); document.write( "\"2x%2B2y=160\"
\n" ); document.write( "\"x%2By=80\" simplified perimeter equation for rectangle.
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\n" ); document.write( "\"-xy=100-s%5E2\"
\n" ); document.write( "\"xy=s%5E2-100\"
\n" ); document.write( "\"xy=40%5E2-100\"
\n" ); document.write( "\"xy=1600-100\"
\n" ); document.write( "\"xy=1500\" eliminated variable s and simplified area equation.\r
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\n" ); document.write( "\n" ); document.write( "SIMPLIFIED SYSTEM:
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\n" ); document.write( "\"highlight_green%28xy=1500%29\" and \"highlight_green%28x%2By=80%29\".\r
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\n" ); document.write( "\n" ); document.write( "Solve the simplified system.
\n" ); document.write( "\"y=80-x\".
\n" ); document.write( "\"x%2880-x%29=1500\"
\n" ); document.write( "\"80x-x%5E2-1500=0\"
\n" ); document.write( "\"x%5E2-80x%2B1500=0\"
\n" ); document.write( "discriminant, \"%2880%29%5E2-4%2A1500=6400-6000=400\".
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\n" ); document.write( "General solution for a quadratic equation:
\n" ); document.write( "\"x=%2880-sqrt%28400%29%29%2F2\"
\n" ); document.write( "\"x=%2880-20%29%2F2\"
\n" ); document.write( "\"highlight%28x=30%29\"
\n" ); document.write( "OR
\n" ); document.write( "\"x=%2880%2B20%29%2F2\"
\n" ); document.write( "\"highlight%28x=50%29\"\r
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\n" ); document.write( "\n" ); document.write( "Length of the rectangle can be either 30 OR 50.
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