document.write( "Question 24233: 2x+3y=21\r
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Algebra.Com's Answer #12881 by AnlytcPhil(1806) $\"\"$ $\"About$

You can put this solution on YOUR website!

You didn't say whether to do it by substitution or\r\n" );
document.write( "by elimination (addition and subtraction).  I'll use\r\n" );
document.write( "substitution\r\n" );
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document.write( " 2x + 3y =  21 \r\n" );
document.write( "-3x - 6y = -24\r\n" );
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document.write( "Solve the second equation for x\r\n" );
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document.write( "-3x - 6y = -24\r\n" );
document.write( "     -3x = -24 + 6y\r\n" );
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document.write( "Divide every term by -3\r\n" );
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document.write( "       x = 8 - 2y\r\n" );
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document.write( "Substitute (8-2y) for x in the OTHER (first) equation\r\n" );
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document.write( " 2x + 3y = 21\r\n" );
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document.write( " 2(8-2y) + 3y = 21\r\n" );
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document.write( "   16-4y + 3y = 21\r\n" );
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document.write( "       16 - y = 21\r\n" );
document.write( "           -y = 5\r\n" );
document.write( "            y = -5\r\n" );
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document.write( "Substitute -5 for y in x = 8-2y\r\n" );
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document.write( "            x = 8 - 2y\r\n" );
document.write( "            x = 8 - 2(-5)\r\n" );
document.write( "            x = 8 + 10\r\n" );
document.write( "            x = 18 \r\n" );
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document.write( "So the solution is (x, y) = (18, -5)\r\n" );
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document.write( "Edwin\r\n" );
document.write( "AnlytcPhil@aol.com

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