document.write( "Question 631809: Solve the following system of equations by elimination process
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Algebra.Com's Answer #397852 by Edwin McCravy(20063)\"\" \"About 
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document.write( "eq.1     4x+4y+3z = 6\r\n" );
document.write( "eq.2     4x+7y+5z = 5\r\n" );
document.write( "eq.3     5x+3y+3z = 7\r\n" );
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document.write( "We will begin by eliminating z from eqs.1 and 3\r\n" );
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document.write( "Multiply eq.1 through by -1 and to it add eq.3\r\n" );
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document.write( "        -4x-4y-3z = -6\r\n" );
document.write( "eq.3     5x+3y+3z =  7\r\n" );
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document.write( "eq.4      x- y    =  1\r\n" );
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document.write( "Next we eliminate the same variable z from eqs. 1 and 2\r\n" );
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document.write( "Multiply eq.1 by -5 and eq. 2 by 3 and add them\r\n" );
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document.write( "        -20x-20y-15z = -30\r\n" );
document.write( "         12x+21y+15z =  15\r\n" );
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document.write( "eq.5     -8x+  y     = -15\r\n" );
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document.write( "We can eliminate y by adding equations 4 and 5\r\n" );
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document.write( "eq.4          x - y  =   1\r\n" );
document.write( "eq.5        -8x + y  = -15\r\n" );
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document.write( "            -7x      = -14\r\n" );
document.write( "                  x  =  2\r\n" );
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document.write( "Substitute x = 2 into eq.4\r\n" );
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document.write( "              x - y  =  1\r\n" );
document.write( "              2 - y  =  1\r\n" );
document.write( "                 -y  = -1\r\n" );
document.write( "                  y  =  1\r\n" );
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document.write( "Substitute x = 2 and y = 1 in eq.q\r\n" );
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document.write( "eq.1        4x+4y+3z = 6\r\n" );
document.write( "        4(2)+4(1)+3z = 6\r\n" );
document.write( "              8+4+3z = 6\r\n" );
document.write( "               12+3z = 6\r\n" );
document.write( "                  3z = -6\r\n" );
document.write( "                   z = -2\r\n" );
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document.write( "Solution:  x=2, y=1, z=-2\r\n" );
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document.write( "Edwin
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