document.write( "Question 266793: Solve By The Addition Method ?\r
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Algebra.Com's Answer #195970 by Edwin McCravy(20056) $\"\"$ $\"About$

You can put this solution on YOUR website!

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document.write( "Pick a letter and pick two equations to \r\n" );
document.write( "eliminate it from:\r\n" );
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document.write( "I'll pick z and the first and second equations\r\n" );
document.write( "to eliminate it from:\r\n" );
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document.write( "Just add them term by term as they are and the\r\n" );
document.write( "z's will cancel out.\r\n" );
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document.write( "Since you can divide that one through by 4, we will\r\n" );
document.write( "go ahead and do that:\r\n" );
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document.write( "Now pick another pair (you have to use one of the\r\n" );
document.write( "same equations you used before, but make sure\r\n" );
document.write( "that you use the third one, the one you \r\n" );
document.write( "haven't used) and eliminate the SAME letter from\r\n" );
document.write( "them.\r\n" );
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document.write( "I'll pick the first and third:\r\n" );
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document.write( "Just add them term by term as they are and the\r\n" );
document.write( "z's will also cancel out.\r\n" );
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document.write( "So now we have reduced it from three equations in three\r\n" );
document.write( "variables, to just two equations in two variables:\r\n" );
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document.write( "We will eliminate the y's by multiplying the first equation\r\n" );
document.write( "through by -5\r\n" );
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document.write( "Add them term by term and get:\r\n" );
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document.write( "Divide both sides by -2\r\n" );
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document.write( "Substitute in \r\n" );
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document.write( "Substitute in any one of the original equations:\r\n" );
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document.write( "So (x,y,z) = (-1,2,1)\r\n" );
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document.write( "Edwin

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