document.write( "Question 52669: Solve the system using the substituion method.
\n" ); document.write( "2x - 5y = 9
\n" ); document.write( "-3x + y = -7 \n" ); document.write( "

Algebra.Com's Answer #35138 by AnlytcPhil(1806) $\"\"$ $\"About$

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Solve the system using the substituion method.\r\n" );
document.write( " 2x - 5y =  9\r\n" );
document.write( "-3x +  y = -7\r\n" );
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document.write( "The substitution method works best when there is\r\n" );
document.write( "a term in one of the variables in one of the \r\n" );
document.write( "equations which has a coefficient of 1 or -1.\r\n" );
document.write( "The second equation has the term \"y\", which has \r\n" );
document.write( "the understood coefficient of 1.\r\n" );
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document.write( "So we solve it for y:\r\n" );
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document.write( "      -3x + y = -7\r\n" );
document.write( "            y = -7 + 3x\r\n" );
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document.write( "Now we substitute (-7 + 3x) for y in  the first\r\n" );
document.write( "equation.\r\n" );
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document.write( "        2x - 5y = 9\r\n" );
document.write( "2x - 5(-7 + 3x) = 9\r\n" );
document.write( "  2x + 35 - 15x = 9\r\n" );
document.write( "      -13x + 35 = 9\r\n" );
document.write( "           -13x = -26\r\n" );
document.write( "              x = 2\r\n" );
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document.write( "Now substitute (2) for x in\r\n" );
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document.write( "            y = -7 + 3x\r\n" );
document.write( "            y = -7 + 3(2)\r\n" );
document.write( "            y = -7 + 6\r\n" );
document.write( "            y = -1\r\n" );
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document.write( "So the solution is (x,y) = (2,-1)\r\n" );
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document.write( "Edwin

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