document.write( "Question 72669: I have tried this several different ways. I don't know how to do it. Please help.\r
\n" ); document.write( "\n" ); document.write( "Solve for x,y,z\r
\n" ); document.write( "\n" ); document.write( "3x+2y-4z=-100
\n" ); document.write( "4x-3y+2z=80
\n" ); document.write( "5x-4y-z=-120 \n" ); document.write( "
Algebra.Com's Answer #52003 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
Solve for x,y,z
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\n" ); document.write( "Well one way, that does not involve matrix operations is multiple elimination:
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\n" ); document.write( "Eq1: 3x+2y-4z=-100
\n" ); document.write( "Eq2: 4x-3y+2z=80
\n" ); document.write( "Eq3: 5x-4y-z=-120
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\n" ); document.write( "Mult eq 2 by 2 and add it to eq1
\n" ); document.write( "3x + 2y - 4z = -100
\n" ); document.write( "8x - 6y + 4z = 160
\n" ); document.write( "----------------------- eliminates z
\n" ); document.write( "11x - 4y = 60
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\n" ); document.write( "Mult eq3 by 2 and add it to eq 2:
\n" ); document.write( " 4x - 3y + 2z = 80
\n" ); document.write( "10x - 8y - 2z = -240
\n" ); document.write( "------------------------eliminates z
\n" ); document.write( "14x - 11y = -160
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\n" ); document.write( "Using these two equations, mult the 1st by 11 and the 2nd by 4
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\n" ); document.write( "121x - 44y = 660
\n" ); document.write( " 56x - 44y = -640
\n" ); document.write( "---------------------subtracting eliminates y, solving for x
\n" ); document.write( " 65x = +1300
\n" ); document.write( "x = 1300/65
\n" ); document.write( "x = 20
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\n" ); document.write( "Let's use 11x - 4y = 60 to find y, substitute 20 for x
\n" ); document.write( "11(20) - 4y = 60
\n" ); document.write( "220 - 4y = 60
\n" ); document.write( "-4y = 60 - 220
\n" ); document.write( "y = -160/-4
\n" ); document.write( "y = +40
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\n" ); document.write( "I'm going to let you find z by substituting for x & y, in one of the original
\n" ); document.write( "equations. Then check all the solutions in one of the other original equations.
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